Landracing Forum

Bonneville Salt Flats Discussion => Build Diaries => Topic started by: generatorshovel on November 17, 2012, 02:57:50 AM

Title: One for the 250cc folk
Post by: generatorshovel on November 17, 2012, 02:57:50 AM
I thought Id share the build the easy way, hopefully I'll get a positive reward for the previous 20 months in hibernation in  Feb 2013 at Lake Gairdner

http://s1195.beta.photobucket.com/user/Blowncbr/story/3099

Tiny
Title: Re: One for the 250cc folk
Post by: Rex Schimmer on November 17, 2012, 06:14:16 PM
Tiny,
Not being a "bike" guy I did not realize that Honda made a 4 cylinder 250. What are the specs, bore and stroke etc.  What is the red line?? what was the rated horse power before blower? what is it now?

Great looking bike! hope you have some luck at Gairdner.

Rex
Title: Re: One for the 250cc folk
Post by: Old Scrambler on November 17, 2012, 07:15:00 PM
I use photobucket......but could not view your pics.........Interested......I know of a builder looking to turbo a CB350F and run it on the salt.....
Title: Re: One for the 250cc folk
Post by: generatorshovel on November 17, 2012, 07:43:03 PM
 The little fours were made in,
Honda CBR250  1986 (I want a head & cams from this model)
CBR250R '87-'89
DOHC (gear driven) 4 valves per cylinder, oval cross section valve springs, titanium ex valves
Bore x Stroke    48.5 x 33.8 mm
 Compression Ratio    11.5:1
45 BHP at 15,000rpm (R)
 
CBR250 RR '90 to '93
40 BHP at 14500 RR from '94 (Jap Government restrictions)
All models redline @ 18.000 rpm (tach lies though, it's actually 17,200rpm)
A "good" stocker will do about 108 mph (the RR's are speed limited)

They were exported to Australia by Honda one year only ('88 ?), most were for the Japanese domestic market.
They have been imported to a few countries by entrerpreneurs after they reach a certain age, and the Jap Gov tax the insurance making them far too costly to keep on the road.
The learner rider regulations here were once limited to 250cc, that's how they became so popular.
I have no idea how much extra power my supercharger gives it Rex, but a guestimate would be in the range of 70 BHP, minus the power needed to drive it, maybe 60 or so ?
Old Scrambler, I don't know why your having trouble viewing the link?
Tiny
Title: Re: One for the 250cc folk
Post by: wobblywalrus on November 19, 2012, 02:16:17 AM
There are some pictures of them on the Australian e-bay.  They are very pretty little bikes.  The ones I saw had full body work.  Its odd.  All of that technology went into a learner bike. 

That bike looks good, Tiny.  Now you need to get someone to make a u-tube movie.  No one has heard a 17,000 rpm 250 four with a blower on it.     
Title: Re: One for the 250cc folk
Post by: generatorshovel on November 19, 2012, 07:11:13 AM
I have a GoPro (it's my data logging system) :-D , too bad I hit the wrong button during the last test run though  :?
There's one word that discribes the sound of a blown 250 four @ 17000 rpm
PAIN

Here's a teaser , this is part throttle only while I was sorting carb/jetting out a few months back.

http://youtu.be/TVr_gdo52so

Tiny
Title: Re: One for the 250cc folk
Post by: Old Scrambler on November 19, 2012, 11:05:52 AM
VERY NICE vid.......Today I see the photos without a problem.  Nice work on the intake plenum 8-)

I'm still looking for that 'test' road :lol: :lol: :lol:
Title: Re: One for the 250cc folk
Post by: wobblywalrus on November 19, 2012, 10:41:59 PM
That looks just like bootleg LSR in Oregon using GPS.  We would be driving on the other side and our tach needles start to move at 0 rpm, not at 6,000.  Nice.
Title: Re: One for the 250cc folk
Post by: dr j on November 24, 2012, 10:42:45 AM
Tiny,
Bike looks great!  Sounds even better!  You have made lots of progress since I last saw photos.  Let me know when, not if, you break my 250cc 4stroke LSR mark of 131.8mph.  At least it will then stay with the Honda marque.
Title: Re: One for the 250cc folk
Post by: bak189 on November 24, 2012, 11:08:47 AM
Great bike....great video....just think how fast it would go on the proper side of the roadway...................................(I build a small sidecar outfit a while back using the 250.c.c four for a guys childeren to play with.. great little engine hard to find here in the States)
Title: Re: One for the 250cc folk
Post by: generatorshovel on November 24, 2012, 05:16:30 PM
Tiny,  Let me know when, not if, you break my 250cc 4stroke LSR mark of 131.8mph.  
Your record is safe Jahl , at least for another year.
I need to do some serious work on my tuck 1st (Jenny craig?)

(http://i1195.photobucket.com/albums/aa399/Blowncbr/Crouch.jpg)

It looked a LOT better before donning 2 cows, and 2 roos which were made into my leathers.

(http://i1195.photobucket.com/albums/aa399/Blowncbr/Tuck.jpg)

Maybe a making fairing would be easier than loosing the gut Iv'e had for 40 yrs ?
Tiny
Title: Re: One for the 250cc folk
Post by: SaltPeter on November 24, 2012, 05:40:39 PM
Making a Fairing vs Loosing weight

Six of one half dozen of the other for mine and my personal Belly Tank

I think I lost 5kgs in sweat making that fairing of mine Tiny :-D.

So go for it and knock both of the Birds down with one throw.

Pete the Croc Wrestler  :cheers:
Title: Re: One for the 250cc folk
Post by: wobblywalrus on January 12, 2013, 11:59:23 PM
People say is is hot where you are.  Here is a picture to look at to cool you down.  A "tit stiffener of a day" as we say here.  Stay safe.
Title: Re: One for the 250cc folk
Post by: generatorshovel on January 13, 2013, 03:20:00 AM
THANKS Wobbly, that worked a treat !
Although the worst of the heat is over for a while, while working in the shed making a scatter shield to protect my innards,,a nice cool change blew in, with a bit of rain.
There's more 110 degree days coming, but with some cooler days thrown in to make it bearable, but,,,the change is a sling off from a tropical cyclone that just missed the west coast, these are the mongrels that have washed out Speedweek the last 2 years,,,,,,,,,,,,,,,,,,,,,,,,,,,,, :?

(http://i156.photobucket.com/albums/t24/generatorshovel/Gutprotector003_zps1b74d640.jpg)

She'll be apples.
Tiny
Title: Re: One for the 250cc folk
Post by: Sam Green on January 18, 2013, 06:11:09 PM
Good luck from England Tiny, keep us informed here. http://forums.sohc4.net/index.php?topic=115527.0

Sam. :cheers:
Title: Re: One for the 250cc folk
Post by: Old Scrambler on January 18, 2013, 06:24:59 PM
Hello Sam :-)

It won't take you very long to pass me up regarding the number of posts on this site.

Title: Re: One for the 250cc folk
Post by: Sam Green on January 18, 2013, 06:41:32 PM
I've been on here for quite a few years Dennis, just not been on for quite a while due to the Drag Racing.
I met Tiny on here when he built his 175 DOHC CB125 postie bike. 8-) 8-) 8-) 8-)

Regards Sam. :wink:
Title: Re: One for the 250cc folk
Post by: generatorshovel on January 18, 2013, 07:20:38 PM
Good luck from England Tiny, keep us informed here. http://forums.sohc4.net/index.php?topic=115527.0

Sam. :cheers:
Thanks Sam, I'll post news, good or bad in the sohc forum also, maybe a ventilated crankcase ?
Here is what they sound like valve bouncing  :-o
http://youtu.be/ctf-CFOJn2w
Title: Re: One for the 250cc folk
Post by: Dr Goggles on January 18, 2013, 08:27:32 PM
T'fer, I've got a loose filling after watching that video, nice one.
Title: Re: One for the 250cc folk
Post by: Old Scrambler on January 18, 2013, 09:36:35 PM
Tiny.....Nice video........so you would fit right in with the local roads in my back yard........I live near the Road America track and have wonderful twisties to ride in all directions.
Title: Re: One for the 250cc folk
Post by: wobblywalrus on January 18, 2013, 10:07:36 PM
That is one nice video that gives me a big smile.  Brings back memories from warm and distant days when I thrashed the life out of my 305 superhawk.  No wobbles in the corners!   
Title: Re: One for the 250cc folk
Post by: generatorshovel on January 19, 2013, 05:21:01 AM
People say is is hot where you are.  Here is a picture to look at to cool you down.  A "tit stiffener of a day" as we say here.  Stay safe.
Now were even Bo. your "cool" pic gave me a long awaited cool change, glad the megga rev video link worked to warm you up.
Title: Re: One for the 250cc folk
Post by: Sam Green on January 19, 2013, 07:38:55 AM
Tiny.....Nice video........so you would fit right in with the local roads in my back yard........I live near the Road America track and have wonderful twisties to ride in all directions.

This is Landracing.com Dennis, only straight line speed in here. :-D :-D :-D :-D :-D :-D :-D :-D

Sam. :wink:
Title: Re: One for the 250cc folk
Post by: Old Scrambler on January 19, 2013, 08:05:08 PM
We ride twisties so we feel comfortable at the salt-flats when we are told to go to IMPOUND :lol: :lol: :lol: :lol:
Title: Re: One for the 250cc folk
Post by: Sam Green on January 19, 2013, 08:20:14 PM
Are you going to the salt again this year Dennis?

Sam. :wink:
Title: Re: One for the 250cc folk
Post by: Old Scrambler on January 20, 2013, 02:55:25 PM
To Sam and All.......YES :-) :-) :-) :-)

My team is ready and we are now preparing the new motor and adding some partial streamlining to the Triumph Cub. I am always on a tight budget and did not have the new motor ready, so we skipped last year. I hope to begin posting some updates in a few weeks.
Title: Re: One for the 250cc folk
Post by: generatorshovel on February 22, 2013, 10:00:45 PM
DNF 2013, hole in #4 piston, turn out near the 2 mile, , , ,

http://www.youtube.com/watch?v=NcDwbVvvxeg&feature=youtu.be

Maybe next time ? (gonna have to try harder to blow it up before leaving for Speedweek 2014 I guess?)


Title: Re: One for the 250cc folk
Post by: tauruck on February 23, 2013, 01:48:32 AM
That sucks. I watched the video. That's racing but you'll be back hey.
Title: Re: One for the 250cc folk
Post by: dr j on February 23, 2013, 01:59:26 PM
Oh Tiny Noooooooooo!  I am so sorry to hear that.  I was really rooting for you with that way cool Honda 250.  I wish I was closer so I could come look at it with you after the meet to do an autopsy.  Thanks for the video post.  Awesome sounding 250cc engine until the extra noises started.
Title: Re: One for the 250cc folk
Post by: generatorshovel on February 23, 2013, 03:35:42 PM
Oh Tiny Noooooooooo!  I am so sorry to hear that.  I was really rooting for you with that way cool Honda 250.  I wish I was closer so I could come look at it with you after the meet to do an autopsy.  Thanks for the video post.  Awesome sounding 250cc engine until the extra noises started.

I think I may have had a crater in #4 piston before I left home,,from when I burned a plug earth strap during a sorting run, making that piston the sacrificial lamb ?
I sort of hope there will be a hole in 2 or 3 as well when I pull the head (damn near impossible to get those plugs out) , although it is not running lean,,it gets a failrly hot thing happening in the combustion chamber.
Although I have an EGT gauge , i decided not to fit it to the bike,,'cos they slow you down,,lol
Title: Re: One for the 250cc folk
Post by: wobblywalrus on February 23, 2013, 10:33:11 PM
Tiny, on no!  At least it was a non-violent engine failure.  Try to post some close up views of your spark plugs and the undersides of your pistons when you get it apart.  It sure sounded good when it was running on all four.
Title: Re: One for the 250cc folk
Post by: Old Scrambler on February 23, 2013, 10:39:39 PM
You were very cool and under control when the bad sounds appeared :cheers:  I think we all feel for your carnage but we still want to see pics of the real thing...........maybe we can learn a lesson to three :lol:
Title: Re: One for the 250cc folk
Post by: generatorshovel on February 23, 2013, 11:37:24 PM
I'll post the autopsy pics when it happens, NP
I had a bloke wanting to buy it early in the week, I didn't say no, just see me later in the week, adding it may have a ventilated crankcase by then, so I was expecting trouble so a mere holed piston was a relief.
1st job is to fit the EGT, 2nd is to drown every bolt in WD40, as this will be the 1st time it's been opened  :oops: and they have a habit of snapping cam bolts.
It may have sounded sweet, but it wasn't, my last test run was sweeter than illegal thought, with a 580 main, I fattened to 600, then the more I thought of its future,,went up to a 640 main, it didn't like it much, but cleared in 4th, up until that, my right wrist looked like it was opening screwtop beers, feeling for the sweet spot, on the previously mentioned test, I hardly had time to select the next gear before hitting 1700 (which is 16200 btw) @ WOT
My cool had vanished after pushing it for 1/2 mile I can assure you  :evil:
Title: Re: One for the 250cc folk
Post by: gearheadeh on February 24, 2013, 03:56:21 AM
Feel for you, Iam a fan of your efforts and look forward to more info.
Title: Re: One for the 250cc folk
Post by: Stan Back on February 26, 2013, 10:30:00 PM
250!!!  How fast did it get to?  Overshot the return road -- none of us has ever done that.
Title: Re: One for the 250cc folk
Post by: generatorshovel on February 26, 2013, 11:58:17 PM
Autopsy pics
(http://i156.photobucket.com/albums/t24/generatorshovel/Hole_zps3569adf6.jpg)

#4 cylinder arrowed (the holed piston was #4)

(http://i156.photobucket.com/albums/t24/generatorshovel/Head_zps2a9d9ad0.jpg)

Water got into #1 as I hosed the salt off , numnuts me didn't re-tighten the plug after removal for inspection saltside.
Tiny

PS, Stan, who overshot what ???? where ?  :? :? :?
Title: Re: One for the 250cc folk
Post by: wobblywalrus on February 27, 2013, 12:37:14 AM
It looks like there were similar piston crown erosion problems on all cylinders and only one had enough of a problem to burn through.  From what I see, this was not the case.  It seems that the problem was on the one cyl only.  A problem with an advanced spark would show up on the cyl on the other end, too.  It looks like it did not, so the timing was OK.  It seems a lean mixture might be the problem.
Title: Re: One for the 250cc folk
Post by: Stan Back on February 27, 2013, 12:42:53 PM
I thought at the end of the video that the rider crossed over what I took to be the return road.
Title: Re: One for the 250cc folk
Post by: DND on February 27, 2013, 03:31:23 PM
Hi Shovel

The crank must look a bit odd with the end throu hanging out a bit to make room for the cam drive stuff.

Its a shame you holed a piston but at least you don;'t have a rod throu the case.

Need more fuel !!!

Sure liked your video and neat sounds too.

Don
Title: Re: One for the 250cc folk
Post by: generatorshovel on February 27, 2013, 04:20:38 PM
I thought at the end of the video that the rider crossed over what I took to be the return road.

Ah HA,,now I understand , that was the Fire & rescue road, once I'd crossed that, the track was clear.
Tiny
Title: Re: One for the 250cc folk
Post by: generatorshovel on February 27, 2013, 04:31:43 PM


The crank must look a bit odd with the end throu hanging out a bit to make room for the cam drive stuff.

Its a shame you holed a piston but at least you don;'t have a rod throu the case.

Need more fuel !!!

Sure liked your video and neat sounds too.

Don

The crank extension is supported by a hybrid ceramic bearing, there was 3 poofteenths room for the shaft to pass the hall effect sensor wire.
Throwing a leg outa bed was expected.
I think I'd started a piston crater during testing, when I burned a plug earth strap #4 plug with #500 main jet, subsequent tests were done with #580, then #600 main, the #580 was not leaning out, the #600 was "safe"
I burnt the piston using a #640 main, the engine didn't clear until hitting 4th gear (the 2 mile ride to the line wasn't such a good idea), and power was down .
The ironic part of the story is that I have an EGT gauge in the filing cabinet, but chose not to use it, as they make you worry too much  :oops:
It will be fitted now, after the horse has bolted
Tiny
Title: Re: One for the 250cc folk
Post by: DND on February 27, 2013, 07:53:46 PM
Hi Tiny

That egt sounds like the way to go , as you sure don't wan't to hurt that neat little engine anymore than you did.

Don
Title: Re: One for the 250cc folk
Post by: wobblywalrus on February 27, 2013, 09:13:36 PM
Did the other three cyls have the same size jets and no problems?  If so, the main jets can be big enough and there is another restriction somewhere in that carb or the float level is off.  Or maybe there is an air leak on that bad cyl.

 
Title: Re: One for the 250cc folk
Post by: generatorshovel on February 27, 2013, 09:50:07 PM
Did the other three cyls have the same size jets and no problems?  If so, the main jets can be big enough and there is another restriction somewhere in that carb or the float level is off.  Or maybe there is an air leak on that bad cyl.

 

One carb, 8 lb boost, leaks would be to atmosphere, not drawn in.
Tiny
Title: Re: One for the 250cc folk
Post by: gearheadeh on February 28, 2013, 01:44:20 AM
Instead of looking at the fuel is it prudent to wonder if that 1 cylinder sitting off by itself will run a little hotter than the others, just enough that it goes over the edge first!
Title: Re: One for the 250cc folk
Post by: generatorshovel on February 28, 2013, 04:47:10 AM
Instead of looking at the fuel is it prudent to wonder if that 1 cylinder sitting off by itself will run a little hotter than the others, just enough that it goes over the edge first!

I hear ya there gearheadeh, #4 needs an excuse for getting itself into trouble all the time
Tiny
Title: Re: One for the 250cc folk
Post by: generatorshovel on March 02, 2013, 04:24:37 AM
Working on this baby is like working on a ladies wristwatch

(http://i156.photobucket.com/albums/t24/generatorshovel/one_zps04bc7ff4.jpg)

(http://i156.photobucket.com/albums/t24/generatorshovel/two_zps666f3caf.jpg)

(http://i156.photobucket.com/albums/t24/generatorshovel/three_zps86940d28.jpg)

(http://i156.photobucket.com/albums/t24/generatorshovel/four_zps95f493f5.jpg)

Pistons appear to be made of unobtanium  :?
Tiny
Title: Re: One for the 250cc folk
Post by: 55chevr on March 02, 2013, 08:38:14 AM
Looks like you need a magnifying glass to install rings ... miniature components.   

Joe
Title: Re: One for the 250cc folk
Post by: Stainless1 on March 02, 2013, 08:59:16 AM
I was just thinking "man that guy had big hands"
Cute motor.
Title: Re: One for the 250cc folk
Post by: DND on March 02, 2013, 01:30:27 PM
Hi Tiny

Did they run the engine in the road race bike blown , or did you add the blower?

The #4 hole chamber & valves looks a bit wet, did it oil in there because of a bad stem seal or oil ring?

Looks like a bore size of about 2.500 dia ?

Don
Title: Re: One for the 250cc folk
Post by: generatorshovel on March 02, 2013, 04:37:27 PM
Hi Tiny

Did they run the engine in the road race bike blown , or did you add the blower?

The #4 hole chamber & valves looks a bit wet, did it oil in there because of a bad stem seal or oil ring?

Looks like a bore size of about 2.500 dia ?

Don



Honda never planned on some nutter fitting a blower Don, they left that job to me
After it holed the piston,,it idled until I made it off the track, there's just a little hole in the piston that let the oil into the chamber until I killed the ign.
Bore size 48.5 mm stroke about 34m ? from memory.
This is an opportunity to lower the static comp. ratio, and get rid of the stock valve overlap I guess, the cost of which scares me. seeing as it was just a "stocking filler" project.
Tiny
Title: Re: One for the 250cc folk
Post by: Jon on March 02, 2013, 06:27:26 PM
Running the standard compression with boost on Methanol shouldn't be a problem I recon.

When you get the fuelling right and stay out of detonation the standard pistons should be ok?

 I'll ask Dave if he knows where to find some pistons, he used to ride one and has mates that have trashed a few.
Have you tried the cbr250.com forum?

jon
Title: Re: One for the 250cc folk
Post by: maj on March 03, 2013, 03:47:39 PM
coating the pistons will help too, instead of doing that to a piston you will get a little further down the track before hurting the head ;)
 
Title: Re: One for the 250cc folk
Post by: generatorshovel on March 03, 2013, 05:28:39 PM
Running the standard compression with boost on Methanol shouldn't be a problem I recon.

When you get the fuelling right and stay out of detonation the standard pistons should be ok?

 I'll ask Dave if he knows where to find some pistons, he used to ride one and has mates that have trashed a few.
Have you tried the cbr250.com forum?

jon

Thanks Jon
coating the pistons will help too, instead of doing that to a piston you will get a little further down the track before hurting the head ;)
 

Yeah Greg, ceramic coating was the plan, maybe some advice on water injection later down the track ? depending on the EGT readings once I get it to the test stage again ?
Tiny
Title: Re: One for the 250cc folk
Post by: wobblywalrus on March 04, 2013, 01:53:15 AM
Arias makes custom pistons.  There is a data sheet you can fill out and send in.  They did the ones for my bike on a special order basis through Triumph Performance.  Maybe Woessner?  Forged pistons are better at dissipating crown heat.

My experience is the bottoms of the pistons will be brown and sometimes black in the centers on the undersides when they get really hot.  It is burned and oxidized oil.  Your pistons do not show that.  It seems the problem that killed your piston happened pretty quick and before everything got hot. 
Title: Re: One for the 250cc folk
Post by: Grandpa Jones on March 04, 2013, 02:02:15 AM
Hi Tiny,

Anyway to tell if all the cylinders are getting the same mixture? The old
draw-thru bikes used an intake manifold that looked like it wouldn't flow
worth a damn, but the design helped equalize the flow to all the cylinders.

I've been trying to find a picture of an example of those manifolds, but
haven't had any luck yet.

Cheers,

Dave






Title: Re: One for the 250cc folk
Post by: stay`tee on March 04, 2013, 02:19:34 AM
 oil + methanol + compression = detonation,  :wink:,
Title: Re: One for the 250cc folk
Post by: JimL on March 04, 2013, 02:33:28 AM
How far up are the plug threads showing color?  Just curious.
Title: Re: One for the 250cc folk
Post by: generatorshovel on March 04, 2013, 04:26:26 AM
Arias makes custom pistons..    Maybe Woessner? -------- I emailed JN @ woesner, awaiting a reply---------  Forged pistons are better at dissipating crown heat.

My experience is the bottoms of the pistons will be brown and sometimes black in the centers on the undersides when they get really hot.  It is burned and oxidized oil.  Your pistons do not show that.  It seems the problem that killed your piston happened pretty quick and before everything got hot.  

(http://i156.photobucket.com/albums/t24/generatorshovel/1_zpsa57d3fcd.jpg)

(http://i156.photobucket.com/albums/t24/generatorshovel/2_zps456eb410.jpg)

(http://i156.photobucket.com/albums/t24/generatorshovel/3_zpse45937ca.jpg)

Title: Re: One for the 250cc folk
Post by: generatorshovel on March 04, 2013, 04:31:13 AM
Hi Tiny,

Anyway to tell if all the cylinders are getting the same mixture?

#4 seems to be missing out, here's the setup (not the carb I use)
(http://i1195.photobucket.com/albums/aa399/Blowncbr/Mounted.jpg)
Title: Re: One for the 250cc folk
Post by: generatorshovel on March 04, 2013, 04:38:12 AM
How far up are the plug threads showing color?  Just curious.

(http://i156.photobucket.com/albums/t24/generatorshovel/1_zpsde3937ec.jpg)

(http://i156.photobucket.com/albums/t24/generatorshovel/2_zps3dce31b3.jpg)

(http://i156.photobucket.com/albums/t24/generatorshovel/3_zpsb8c08805.jpg)

(http://i156.photobucket.com/albums/t24/generatorshovel/4withhole_zpsff4f45f2.jpg)

When testing #4 burnt 1/2 the earth strap from the plug (#500 main) , I had a "safe" #640 in it when the piston melted, I will never know if I began to melt the piston then, or not, if so, the piston would have been very weak on the crown
While pulling the piston off the rod, the pin was tight,,and the top ring was also tight, poor little piston had a hard life

All the plugs show only up to one thread discolored,
Title: Re: One for the 250cc folk
Post by: DND on March 04, 2013, 03:51:54 PM
Hi Tiny

Maybe a new manifiold is in order, a log or plenum style with the same length runners.

The one you have now just might be giving the different holes different mixtures, worth a little fab time to make a more efficent system so each of the 4 guys are getting the same load.

Don
Title: Re: One for the 250cc folk
Post by: maj on March 04, 2013, 04:01:32 PM
I think the same as Dave and Don
looks like your getting less fuel on the hurt cylinder
my best guess ,  supercharger is probably directing the methanol as a liquid more than vapor and flinging it towards the upper tubes from the lower half of the supercharger
only 10% less flow to the cyl could be enough to cause problems
Title: Re: One for the 250cc folk
Post by: generatorshovel on March 04, 2013, 04:26:46 PM
Thanks for your input guys, there's nothing like a think tank
The plenum change makes sense , it might even end up being easier to fit,,surely it won't be harder,,,,,
Funnily enough, the original plan was for a "normal" type plenum, but was dropped after trying to think like a pocket of fuel / air mixture, and how it would behave,,best I revert to not overtaxing my last 3 remaining brain cells, and do more research,
EDIT,,,
Space is always a problem, the frame rails do not allow any other intake at the moment, so it's time to reinvent the wheel,,,,,
My co-builder always wanted to build a sidecar,,this engine is a test bed for it,,,I think , with all the input received from you guys , and the gut feeling I've had regarding the plenum appears to be true,
I absolutely HATE working on fiddly things, so the new frame design needs to allow the engine, or parts attached to it to be easily removed when needed . I'm thinking no backbone, maybe a removable one, , structural strength can be designed without the need for a backbone, and the different layout of a sidecar frame will allow for thinking outside the square ?
Although designing a better plenum will be a challenge (I still worry about cylinders #1 + #4 not receiving as much mix as #2 + #3). but if I build a blower / plenum test bench and measure each cylinders flow rates while spinning the blower with a drill or simillar, changes can be made inside the plenum untill I'm happy with the result ?
Long & low is the plan, detachable 3rd wheel on a stick  maybe ?
Tiny
Title: Re: One for the 250cc folk
Post by: Peter Jack on March 04, 2013, 04:59:27 PM
While you're at it I'd be tempted to make the flanges out of somewhat heavier material. A leak in one location could definitely affect the mixture in the area of the leak.

Pete
Title: Re: One for the 250cc folk
Post by: JimL on March 04, 2013, 09:11:08 PM
 I see heat line almost to the top of the threads.  Thats a little spooky.  Not the carbon line, but the metal discolor.

Thats too far for extended run.  Once you get that kind of heat flowing through the shell, youve leaned out and the pistons are toast.  It takes time and distance to heat soak an aluminum head to the point that it stops accepting more because the only path left for the calories is into the coolant.

Many of us with marginal cooling capacity, for our power output, try not to sink too much heat into the head before we start our run.  When we get it right, the engine gets about good in the mile that matters, though it is feeling a little raggedy in the first mile or so.

I havent blown an engine up since I was taught to do it that way.  My plugs come out without a color line, so I could be a little more brave but I have that Italian disease...."mufunzalo".

Anybody else here seeing that hot steel color way up the threads?  I aint that sharp on this stuff, so steer him right if I'm off base!

Thanks
Title: Re: One for the 250cc folk
Post by: wobblywalrus on March 04, 2013, 09:30:26 PM
The bottoms of the pistons show that things were getting pretty hot in all four combustion chambers.
Title: Re: One for the 250cc folk
Post by: DND on March 04, 2013, 10:31:23 PM
I was looking at your blower pic and it looks like you can see the bolt shank between the two center flanges, oops not too good as this would leak out your boost.

Like Peter Jack says you need thicker flanges and make sure they are flat after your welding too.

That sure is a neat little blower, what was its main use?

Don
Title: Re: One for the 250cc folk
Post by: Grandpa Jones on March 04, 2013, 10:59:13 PM
Hi Tiny,

Found some intake manifold pictures on the SOHC Honda forum. Didn't want to post the pix
without permission, so here is a link.

http://forums.sohc4.net/index.php?topic=101267.100 (http://forums.sohc4.net/index.php?topic=101267.100)

I guess with the inlet being offset from the runners, the flow from the turbo/blower can't
favor one runner over another. Boost/mixture hits the "wall", and is diffused into the plenum.

Charlie Toy went fast with a draw-thru turbo, scroll down the page and you can see this
type of manifold on one of his bikes.

http://www.landracing.com/forum/index.php?topic=3972.0 (http://www.landracing.com/forum/index.php?topic=3972.0)

Cheers,

Dave
Title: Re: One for the 250cc folk
Post by: wobblywalrus on March 04, 2013, 11:11:35 PM
Type "48.5mm pistons" into your search engine.  Aliexpress.com pops up.  They have your pistons.  They are made by lpmotoparts.

Send me a pm if you can't find them.
Title: Re: One for the 250cc folk
Post by: generatorshovel on March 05, 2013, 12:45:01 AM
JimmyL, the plugs have oxidised quite a lot sinse they were pulled, I pulled # & #4 on the salt (the others take 1 hr) #1 had thread heat discolourisation on 1 side of the 1st thread only, and 4 was contaminated when the hole appeared
#2 & #3 had one complete thread discoloured when they were eventually pulled

Wobbly, the engine has done 24,000 liles before I bought it, I suspect the gold under the piston crowns was a result of the test ride when I melted the plug from #4
I don't trust the Chinese, they have already planted a virus enabling them to change a cut & pasted email address so they got $200 of my hard earned,,PayPal told me to go plait my sh*t
Honda make good pistons, but not good enough,,custom flat top forged with ceramic tops should be up to the task, an egt gauge is a must
I wont buy chinese,,EVER, if I know who made it first

DND,,the blowers were used on Subaru Vivito 660cc delivery vans in Japan only-- point taken on the flanges (they were 8mm plate before being milled flat---

Dave,,anything I've posted is considered public , anyone can re-post, but thanks for the consideration you showed
Tiny
Title: Re: One for the 250cc folk
Post by: DND on March 05, 2013, 01:09:08 AM
Tiny you were saying that the coated pistons would be a good deal, maybe not if the heat kills your 4 valve head.

Might be better to hole a piston than kill that neat little 4 valve head !!

Don
Title: Re: One for the 250cc folk
Post by: Dr Goggles on March 05, 2013, 07:14:24 AM
I absolutely HATE working on fiddly things, so the new frame design needs to allow the engine, or parts attached to it to be easily removed when needed . I'm thinking no backbone, maybe a removable one, ,

just make up some mini exhaust type flanges, or a pipe sleeve for the top tube , or tell me to GFM, no, not "go find mum" :-o

Spoke to Frase on Sun night, thanked him for feeding us orphans , he told me the high point of the week was the old fellas whinging about the chili c.c, I brought up the big-block, he changed the subject. :roll: :roll:
Title: Re: One for the 250cc folk
Post by: generatorshovel on March 05, 2013, 03:11:28 PM
Tiny you were saying that the coated pistons would be a good deal, maybe not if the heat kills your 4 valve head.

Might be better to hole a piston than kill that neat little 4 valve head !!

Don

Don, A ceramic coating may give me some time while I sort the mixture, heads are a dime a dozen if you are patient, valves, they are another story,,,,

Goggz,,GFY  :lol:
Wilso boned up when I told him the plan, and started muttering things like,,110" wheelbase,,rear engine, inverted wing chair structure, doubling as fuel tank nsr single sided swing arm,,mutter mutter,,
Still trying to get to Sunshine to see a man about a dog,,,
T'fer
Title: Re: One for the 250cc folk
Post by: wobblywalrus on March 07, 2013, 12:33:02 AM
Tiny, that idea of a log type plenum with equal length intake stacks is a good one.

The Triumph runs on pump gas on the street.  It is near sea level here and it is jetted for unleaded non ethanol pump gas on the dyno.  ERC MULB, an unleaded racing gas, or ERC 110K, a leaded racing gas are used at B'ville which is at just over 4,000 feet elevation.  The bike runs OK on those race gasolines with no jetting changes on the salt.  This tells me those race gasolines may be oxygenated and I could burn up the engine if I used them at lower elevations - unless I jetted the carbs richer.

I am not familiar with how you did the jetting or the equivalence of Australian race and pump gas.  It is something to consider if the bike was jetted for pump gas and raced with an oxygenated one.
Title: Re: One for the 250cc folk
Post by: generatorshovel on March 07, 2013, 03:39:52 AM
Wobbly, gas was never considered with the engine mods, due to the compression ratio and heat generated by compressing the fuel/ air
Methanol helps cool the charge, if let the engine temp get to operating temp before a test run, it always came back cold (according to the water temp gauge), it would melt itself using gas real quickly.
It looks as though the Chinese might be the only "new" piston option, Ive asked for the alloy type and process used in their manufacture and assurance they would meet OEM Honda ill all aspects,
I had a  a stoke of luck today, stumbling across 10 intake, and 10 exhaust (titanium) valves, previously, the only ex valves I could find were in the UK,,and $47 each!, but I bought all 20 for $400 , I wonder if I'll need any now,,ha ha .
I had these spun early in the build than changed my mind,,they will come in handy when I revert to plan "A"
(http://i1195.photobucket.com/albums/aa399/Blowncbr/stackdimension.jpg)
Tiny
Title: Re: One for the 250cc folk
Post by: generatorshovel on March 08, 2013, 03:43:48 AM
I had some GREAT news from John Noonan today,,,Woosner will take on the custom piston job !, excellent !
Thank you JN  :cheers:
Title: Re: One for the 250cc folk
Post by: Stainless1 on March 08, 2013, 09:11:14 AM
John Noonan is the USA rep for Wossner and an accomplished Landspeed Racer.  Anyone with a custom piston requirement should call or email him before buying elsewhere.  Wossner USA gives a LSR discount.  My new -6.5cc dish Busa pistons just showed up yesterday.  John also worked in a great price for custom rods. 
Now back to your regular programming...
When ordering custom pistons for that baby motor, be sure to buy plenty of extras... that will ensure that you won't need them.
Title: Re: One for the 250cc folk
Post by: Queeziryder on March 08, 2013, 10:39:58 AM
+1 to what Stainless said.

John was able to help out with a one off for my dad's classic  :cheers:
Title: Re: One for the 250cc folk
Post by: maj on March 09, 2013, 03:49:41 PM
couple of custom sets coming from John for our 750's too  :cheers:
Title: Re: One for the 250cc folk
Post by: generatorshovel on March 22, 2013, 10:17:05 AM
The piston order has to wait until my block comes back from re-boring (I wish I'd measured a few things as I tore it down)
I finally found the "early" model cams I've been after, with buggerall overlap, and more suited to the blown application,these will pull the power down a 1000 rpm or so, allowing for a bit less blower under drive (if needed) and more boost, and a tad more valve / piston clearance.
Stock head gasket is .3mm thick, the new copper one will be .5mm, as much extra as I can use without upsetting the backlash of the gear driven cams.
I'm planning 10/1 for the forged pistons (down from 11.7) which should still give me 16.7/1 with 10 lb boost (I'm trusting my night shift memory there)
 Two Bob Engineering (myself & co-builder Wilso) are off down to Melbourne next week to pick up a spare bottom end we were given 6 mnths back, Doc Goggles used his light coloured molskins to soak up its viscous vomit when removing it from a car trunk  :roll:
We are also picking up another '87 CBR250 r in a barter deal with a couple of leading link sidecar front ends (hopefully) Wilso may fit as a favour.
While on a shopping frenzy, we will get a Honda NSR 150 single sided swingarm and wheel, (maybe 2 ?) for "sidecar stock"
I'll be broke once I get the pistons, but that's LSR, and it saves "wasting" money on things like food and booze eh !
Tiny
Title: Re: One for the 250cc folk
Post by: Old Scrambler on March 22, 2013, 09:57:51 PM
Thanks for keeping us posted..............Just a note.........Best piston fit is usually attained by sending the pistons along with the block for boring. Hopefully your piston supplier will send skirt clearance specs so you can check your bores.  I only have to deal with one piston but its not perfectly round. That's what I get for using 50+ year old parts made in the UK.
Title: Re: One for the 250cc folk
Post by: generatorshovel on March 22, 2013, 11:46:45 PM
Thanks for keeping us posted..............Just a note.........Best piston fit is usually attained by sending the pistons along with the block for boring. Hopefully your piston supplier will send skirt clearance specs so you can check your bores.  I only have to deal with one piston but its not perfectly round. That's what I get for using 50+ year old parts made in the UK.

Ya never too old to learn new tricks, apparently,,
"Piston to Bore Clearance: Wossner pistons already have the recommended clearance built in. Skirt diameter is smaller than the recommended bore size (see sizing on box). Some applications: Nitrous, supercharged, turbo, and cold water marine engines may need more than the recommended clearance.

Wossner pistons are measured 90 degrees from the pin axis at the widest point on the piston skirt.

Wossner clearances are set before coating. Coatings are 0.012mm (0.00047”) thick and should be deducted when measuring for piston to bore clearance. "
Title: Re: One for the 250cc folk
Post by: Dr Goggles on March 23, 2013, 12:51:47 AM
Hey Teef,

Tuesday should be fine .....depending on who's coming with you I think we should go out for a feed of Vietnamese.

No, Vietnamese food.

The motor is still sitting on the porch surrounded by anti corrosion treatment,well, what didn't get on my trousers, strangely no-one has complained. :roll:

If Wilso's coming he can have his tarp back.....

I'll try and think up some sort of "Care Package" it's what the seppo's do when someone drops in apparently........
Title: Re: One for the 250cc folk
Post by: generatorshovel on July 29, 2013, 04:04:05 AM
After countless hours crawling around in lalaland  looking for ideas on plenum design, I found this.
http://youtu.be/X3ecq8MNfk0

Made these
(http://i1195.photobucket.com/albums/aa399/Blowncbr/five_zpsac477010.jpg) (http://s1195.photobucket.com/user/Blowncbr/media/five_zpsac477010.jpg.html)


(http://i1195.photobucket.com/albums/aa399/Blowncbr/MatchPortplenum001_zps70736d53.jpg) (http://s1195.photobucket.com/user/Blowncbr/media/MatchPortplenum001_zps70736d53.jpg.html)
Title: Re: One for the 250cc folk
Post by: generatorshovel on July 29, 2013, 04:05:24 AM
More pics


(http://i1195.photobucket.com/albums/aa399/Blowncbr/two_zps52cea2e0.jpg) (http://s1195.photobucket.com/user/Blowncbr/media/two_zps52cea2e0.jpg.html)

(http://i1195.photobucket.com/albums/aa399/Blowncbr/four_zpse985ccfc.jpg) (http://s1195.photobucket.com/user/Blowncbr/media/four_zpse985ccfc.jpg.html)
Title: Re: One for the 250cc folk
Post by: generatorshovel on July 29, 2013, 04:09:33 AM
(http://i1195.photobucket.com/albums/aa399/Blowncbr/three_zps05efff6b.jpg) (http://s1195.photobucket.com/user/Blowncbr/media/three_zps05efff6b.jpg.html)

(http://i1195.photobucket.com/albums/aa399/Blowncbr/five_zps6b428f86.jpg) (http://s1195.photobucket.com/user/Blowncbr/media/five_zps6b428f86.jpg.html)

I need to think about what to do with the ends, although I have a few ideas, perhaps widening the floor a little to avoid a dead air area on the outer intakes

Feel free to comment on, criticize , agree or disagree with the design. actually, any comments would be greatly appreciated before I progress any further
Tiny
Title: Re: One for the 250cc folk
Post by: maj on July 29, 2013, 04:19:57 AM
Tiny its not to dissimilar to how i have built a few turbo plenums
but draw through methanol is not something i have tried
all i could suggest is keep the sheet size up, 3mm or better ,
with water injection i put a 1/16 drain hole at the lowest point  , but although the drain could be handy i expect a steady stream of air/fuel at combustable ratios would be a disadvantage 
Title: Re: One for the 250cc folk
Post by: generatorshovel on July 29, 2013, 05:01:37 AM
Thanks Greg


all i could suggest is keep the sheet size up, 3mm or better ,

5mm top and bottom, 3mm rolled, 3mm tube sectioned
with water injection i put a 1/16 drain hole at the lowest point  , but although the drain could be handy i expect a steady stream of air/fuel at combustable ratios would be a disadvantage  
Yep, Mk1 had a drain at the lowest point, this one will have 2, one at bottom of blower outlet, and another lower left of the plenum floor, perfect when sitting on the side stand

I wouldn't go the draw thru route again, makes it difficult to use an intercooler, I have 'nuff strife now with fuel dropping out of suspension when warming up, but by far the best solution would be EFI, but I doubt I have enough decades left to get my head around that, being mostly uncharted territory on these 250 fours, although there's a guy in Ireland making good headway using microsquirt
Tiny
Title: Re: One for the 250cc folk
Post by: Jon on July 29, 2013, 08:20:14 AM
Looks good Tiny, any room to get a little more distance between the top of the bell mouths and the roof of the plenum, think I remember reading 1.5 diameters somewhere.

What did you get the green anodizing off with?, I've not done much alloy welding, guessing it needs to come off first.

jon
Title: Re: One for the 250cc folk
Post by: JimL on July 29, 2013, 09:21:46 AM
I've noticed in a couple Honda plenums that I scrapped, the center two velocity stacks are a couple millimeter longer than the end two.  I have seen this in other stuff, also, and thinking there must be a reason.  It might be just Helmholtz noise abatement.  Perhaps worth some study?

Even my V-twins run best with uneven tuned length between the intakes, though its a different problem.

JimL
Title: Re: One for the 250cc folk
Post by: generatorshovel on July 29, 2013, 06:55:09 PM
Looks good Tiny, any room to get a little more distance between the top of the bell mouths and the roof of the plenum, think I remember reading 1.5 diameters somewhere.

What did you get the green anodizing off with?, I've not done much alloy welding, guessing it needs to come off first.

jon
No Jon, theres 11mm between the plenum top, and the frame, and the intake flange on the head is 10mm tall, ladies wristwatch stuff
I wasnt looking forward to removing the green stuff, but mounted the units in the lathe and it came off real easilly using some coarse abrasive sanding sheets, then polished with #400 wet/dry
I've noticed in a couple Honda plenums that I scrapped, the center two velocity stacks are a couple millimeter longer than the end two.  I have seen this in other stuff, also, and thinking there must be a reason.  It might be just Helmholtz noise abatement.  Perhaps worth some study?

Even my V-twins run best with uneven tuned length between the intakes, though its a different problem.

JimL
Jim,
I think , from info gathered from other forums, the long / short stack lengths are to help the spread of power ?

Tiny
Title: Re: One for the 250cc folk
Post by: fredvance on July 29, 2013, 07:07:02 PM
On a stock Busa, they have two VS lengths. This is for better streetability. The first thing we do is put all short VS, for more high rpm HP.
Title: Re: One for the 250cc folk
Post by: SaltPeter on July 30, 2013, 01:16:56 AM
Is there different intake requirements in a forced induction engine?

I have found that the shape of my airbox on my 2 stroke RGV has quiet a significant impact on the way it develops power.

Pete :?
Title: Re: One for the 250cc folk
Post by: generatorshovel on August 04, 2013, 07:05:15 PM
Is there different intake requirements in a forced induction engine?

I have found that the shape of my airbox on my 2 stroke RGV has quiet a significant impact on the way it develops power.

Pete :?
I think the airboxes flex somewhat Pete, helping to even out the intake pulses, Blown engines get what they are given, hopefully, if well thought out, it's what they need ?

Getting closer to welding the plenum, BOV will be on top this time, with potential fireballs directed to the left, and down away from ME.
(http://i1195.photobucket.com/albums/aa399/Blowncbr/4copy_zps97879e0d.jpg) (http://s1195.photobucket.com/user/Blowncbr/media/4copy_zps97879e0d.jpg.html)

(http://i1195.photobucket.com/albums/aa399/Blowncbr/6copy_zps7266cce5.jpg) (http://s1195.photobucket.com/user/Blowncbr/media/6copy_zps7266cce5.jpg.html)
Tiny


Title: Re: One for the 250cc folk
Post by: generatorshovel on August 15, 2013, 02:21:24 AM
Great week here too, no racing, but,,,,,,

(http://i156.photobucket.com/albums/t24/generatorshovel/2_zps2ceaa630.jpg) (http://s156.photobucket.com/user/generatorshovel/media/2_zps2ceaa630.jpg.html)

JN, this is what I wanted mate  :wink:

(http://i156.photobucket.com/albums/t24/generatorshovel/5_zps49cbabf7.jpg) (http://s156.photobucket.com/user/generatorshovel/media/5_zps49cbabf7.jpg.html)
Tiny
Title: Re: One for the 250cc folk
Post by: generatorshovel on November 09, 2013, 03:47:46 AM
Work on the 250 continues.the piston oilers are plumbed
(http://i156.photobucket.com/albums/t24/generatorshovel/nekidpipes_zps7bbec50e.jpg) (http://s156.photobucket.com/user/generatorshovel/media/nekidpipes_zps7bbec50e.jpg.html)

The fuel supply problems are solved (thanks Holley)

(http://i156.photobucket.com/albums/t24/generatorshovel/Mikholley_zps314441cd.jpg) (http://s156.photobucket.com/user/generatorshovel/media/Mikholley_zps314441cd.jpg.html)

I sure hope the new plenum works ok (next job is to divert potential BOV fireballs away from the rider)

(http://i156.photobucket.com/albums/t24/generatorshovel/notmushroom_zps62035cc5.jpg) (http://s156.photobucket.com/user/generatorshovel/media/notmushroom_zps62035cc5.jpg.html)


(http://i156.photobucket.com/albums/t24/generatorshovel/tiedown_zps6c040845.jpg) (http://s156.photobucket.com/user/generatorshovel/media/tiedown_zps6c040845.jpg.html)

(http://i156.photobucket.com/albums/t24/generatorshovel/gutshield_zps65ad0ca4.jpg) (http://s156.photobucket.com/user/generatorshovel/media/gutshield_zps65ad0ca4.jpg.html)

(http://i156.photobucket.com/albums/t24/generatorshovel/package_zpsf9294a86.jpg) (http://s156.photobucket.com/user/generatorshovel/media/package_zpsf9294a86.jpg.html)

Tiny


Title: Re: One for the 250cc folk
Post by: tauruck on November 09, 2013, 07:53:22 AM
You've come a long way and been busy!. It looks great. Big power jump there. :cheers:
Title: Re: One for the 250cc folk
Post by: wobblywalrus on November 09, 2013, 04:02:16 PM
Looks good, Tiny.  There is nothing like it.
Title: Re: One for the 250cc folk
Post by: generatorshovel on February 16, 2014, 04:14:01 PM
The learning curve continues,,,,,
With the camshaft change, came 15 lb of boost, which, although it creates GOBS of power, it also gives me nightmares, so Iv'e gone from 25% underdrive on the blower, to 38%, which , hopefully, will get the boost level back to where it was with stock cams (10 lb)
Time is running out, a planned test run yesterday was halted by a sick coil, something that only appeared when the weather cooled down (from 110 degrees, to 60  :-o ) , the bike would not start, just tease.
Team member Bob, has spare coils, which I'll try later today.
Short clip of a warm up run with 15 lb boost

http://youtu.be/cS5dAJz90uo

The additional power resulted in clutch slip also, I discovered my "test tank" lacked adequate venting, and the thermostat was opening too slow, more jobs for Bob (me)

Tiny
Title: Re: One for the 250cc folk
Post by: tauruck on February 16, 2014, 11:01:28 PM
It sounds good. :cheers:
Title: Re: One for the 250cc folk
Post by: wobblywalrus on February 17, 2014, 12:51:29 PM
The Burt Munro method.  Find a seldom used road and test there.
Title: Re: One for the 250cc folk
Post by: Dr Goggles on February 17, 2014, 02:35:35 PM
Nice work T'fer....Now, are we pitting together?
Title: Re: One for the 250cc folk
Post by: generatorshovel on February 17, 2014, 03:22:37 PM
Nice work T'fer....Now, are we pitting together?

Yup. Chris Bryson wants a spot saved too.

LASLO WON'T START !

I'm workin' on it,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, :? :? :?
Tiny
Title: Re: One for the 250cc folk
Post by: Dr Goggles on February 17, 2014, 03:54:53 PM
You mean Agent 86?....I was just thinking about him the other day,then last night I was talking to Luke Zietar the guy making the 3d salt movie,he mentioned Chris , I laughed and said "he's a classic",he responded,"um,you're alll classics......"
You too Tiny.......

Title: Re: One for the 250cc folk
Post by: Rasmussen on February 22, 2014, 02:33:27 AM
looking real good tiny, it`s definitely getting crowded in there. Sounds great too :-D
Title: Re: One for the 250cc folk
Post by: generatorshovel on February 22, 2014, 03:30:11 AM
looking real good tiny, it`s definitely getting crowded in there. Sounds great too :-D

I'm beat, for this year, can't sort the lean out condition Iv'e got , not without trying, I can assure you  :-(

I'm maxed out with the needle jet/needle combo, any richer it won't burn the mix, mind you , it sounds good WHOOF. WHOOF'n on deceleration , I'm sure the blue flames would look good at night !

I'll try going back to a jet combo I know is good up until the main jet takes over, and supplement it with an adjustable power jet ?

Another worry is #1 cylinder running 100 degrees F hotter than the rest, until I put the gas carb on to purge the alcohol out of everything idling , all 4 pots run at the same temp ?
Tiny
Ps, Goggs, we will cya saltside, we leave thursday, plenty of room for beer and tucker now too !
Title: Re: One for the 250cc folk
Post by: Rasmussen on February 22, 2014, 04:31:21 AM
That sucks :x, but at the same time is very interesting, as a very bad leanout is exactly what I´m dealing with at the moment. Have just posted about it in my thread. We´ll get this fixed! no surrender :-D
Title: Re: One for the 250cc folk
Post by: gearheadeh on February 22, 2014, 10:46:08 AM
Tiny, I like the idea of adapting the Holley float bowl. They make high flow and super high flow needle and seats for alcohol.
What have you done to eliminate that the seats are not flowing enough under high demand, Also- how about the upstream piping and the shut off valve. Are they able to keep up with the flow demands?
Hoping you do well, cheering for you.   :cheers:
Title: Re: One for the 250cc folk
Post by: wobblywalrus on February 22, 2014, 01:00:43 PM
The advice given to me is to fill the tank up to the top before the race, use a high flow fuel valve like a guzzler, and a well flowing tank vent like a hose projecting up from the gas cap.  The solution might be something really simple.
Title: Re: One for the 250cc folk
Post by: generatorshovel on February 22, 2014, 04:31:30 PM
Tiny, I like the idea of adapting the Holley float bowl. They make high flow and super high flow needle and seats for alcohol.
What have you done to eliminate that the seats are not flowing enough under high demand, Also- how about the upstream piping and the shut off valve. Are they able to keep up with the flow demands?
Hoping you do well, cheering for you.   :cheers:

Flow from the bowl, measured with drain removed, out of the float bowl(s) exceeds the 1.8 liter needs of my engine @ wot, by 300 ml
I'm using a Mallory 70 gallon / hr pump @ 3.5 psi
The problem I'm thinking, is once boost is at max (9 psi at the moment)the fuel requirements go up, the fuel/ air ratio remains the same, but the air is compresses, the fuel is not (liquids don't compress, even in the droplet state) so the quantity of air in the cylinder is increased, but being a draw thru system, the fuel is introduced before the air is compressed.
Starting with a #640 main, I rode,shot video of the gauges, upped the jet to 680, repeated the test, then upped to a jet drilled to equal a 710 main, there was no difference in the a/f ratio above 3/4 throttle with either of the larger jets, which leads me to think Ive reached the flow limits of the "good" mid range jetting in supplying more fuel at wot.
I cannot increase the flow past the needle and needle jet to enable enough fuel to pass thru the main jet,  between the needle & needle jet diameter/ orifice without changing the a/f ratio from 1/4 to 3/4 throttle, which the engine hates when it's too fat.
Sure, months of cutaway mods, needle mods may cure the problem, But I'm thinking some kind of adjustable powervalve added to the carb may be the answer.
Tiny
Title: Re: One for the 250cc folk
Post by: Sam Green on February 22, 2014, 05:33:58 PM
Hi Bob, sorry to hear the bad news, ya really don't want to go messing them new pistons up if you can't get it to fuel right.
Have you ever thought of going old fashioned and using the likes of a Wal Phillips Fuel injector.
https://www.google.co.uk/search?q=wal+phillips+fuel+injector+instructions&rlz=1C1EODB_enGB531GB532&espv=210&es_sm=93&tbm=isch&imgil=o8ZT3VzOS0nmnM%253A%253Bhttps%253A%252F%252Fencrypted-tbn3.gstatic.com%252Fimages%253Fq%253Dtbn%253AANd9GcTI_N1z959qIRV0sORZOMWi-CfYGxnTHc2pIa5iz7gZV6Op45R6%253B742%253B690%253BioG5FGAX7mW85M%253Bhttp%25253A%25252F%25252Fwww.racinglambrettas.com%25252Fhowthetdidit%25252Fwalphillips.html&source=iu&usg=__BdhjYjXbnRkOXVPWa7OojRq4PGE%3D&sa=X&ei=kCIJU4fdNbCO7QbDm4GAAg&ved=0CDUQ9QEwAQ&biw=1280&bih=963#facrc=_&imgdii=_&imgrc=o8ZT3VzOS0nmnM%253A%3BioG5FGAX7mW85M%3Bhttp%253A%252F%252Fwww.racinglambrettas.com%252Fhowthetdidit%252FWalPhillips11.jpg%3Bhttp%253A%252F%252Fwww.racinglambrettas.com%252Fhowthetdidit%252Fwalphillips.html%3B742%3B690

It's simplicity in itself, just a jet and a butterfly, Ok, I wasn't blown but I used one to get Methanol into my little 175cc LSR back in the 60s and 70s. A lot of the drag race guys used them on all types of blown machines. They are just gravity fed so the only thing you have to make sure of is that you don't turn the fuel on until the motor starts to spin. Also you have to make sure you turn the fuel off when you kill the motor. Just a thought my friend.

Regards Sam. :cheers:
Title: Re: One for the 250cc folk
Post by: generatorshovel on February 22, 2014, 06:10:47 PM
Yeah Sam, 'ol Wall has entered my brain, I had a mate in the early 70's who used /em on his YDS5 250 yammy, that thing shattered eardrums, shook windows and frustrated it's owner, it was faster in 3rd than it was stock, but wouldn't pull any taller gears, and tended to spit broken chains onto the ground when dragging,,lol,,mamories,,,,,

I think I'll go with the power/thunder/adjustable jet idea at this stake, but I'll have to make it I think,,I already have a 90 degree barbed elbow on my float bowl drain plug, just waiting for another job, other than draining the float bowl, and checking fuel level at a glance.
Title: Re: One for the 250cc folk
Post by: Sam Green on February 22, 2014, 07:10:42 PM
When I got it from Wal, it came ready jetted for Methanol.
I fitted it, turned on the ignition and fuel and spun the rear wheel.
It went straight to a perfect tick over. haha
I never touched it all the time I had it.
It did run very rich but performance wasn't impaired. I had to drop the oil after two runs over the quarter and at the end of a full flyer.
What looks like smoke in the second picture is un burnt fuel coming out of the exhaust.
Title: Re: One for the 250cc folk
Post by: generatorshovel on September 08, 2014, 04:46:45 AM
After a winter rest, tuning has recommenced , disregarding the A/F gauge that was lying all the time (long story)
I went back to similar jetting I had when I melted the piston, but with a fuel pump this time, eliminating the risk of inadequate fuel supply to the carb.
After a flog today, 1/4 mile (or so) @ WOT in 6th I killed ign etc, and pulled the plugs (methanol fuel)
Opinions sought please
I think I'm close to the right side of safe(but not safe , yet), by the look of the plugs ?
(http://i156.photobucket.com/albums/t24/generatorshovel/three_zps3f17d2f3.jpg) (http://s156.photobucket.com/user/generatorshovel/media/three_zps3f17d2f3.jpg.html)

(http://i156.photobucket.com/albums/t24/generatorshovel/one_zpsd06cf251.jpg) (http://s156.photobucket.com/user/generatorshovel/media/one_zpsd06cf251.jpg.html)

(http://i156.photobucket.com/albums/t24/generatorshovel/two_zps28dfabf5.jpg) (http://s156.photobucket.com/user/generatorshovel/media/two_zps28dfabf5.jpg.html)

(http://i156.photobucket.com/albums/t24/generatorshovel/five_zps83afe738.jpg) (http://s156.photobucket.com/user/generatorshovel/media/five_zps83afe738.jpg.html)

(http://i156.photobucket.com/albums/t24/generatorshovel/six_zps4c76a0c7.jpg) (http://s156.photobucket.com/user/generatorshovel/media/six_zps4c76a0c7.jpg.html)

(http://i156.photobucket.com/albums/t24/generatorshovel/four_zpsc71bf41d.jpg) (http://s156.photobucket.com/user/generatorshovel/media/four_zpsc71bf41d.jpg.html)
Title: Re: One for the 250cc folk
Post by: tauruck on September 08, 2014, 07:30:43 AM
Wee bit lean. :wink:
Title: Re: One for the 250cc folk
Post by: RansomT on September 08, 2014, 08:32:36 AM
Wee bit lean. :wink:

Agree'd.

and keep an eye on those electrodes.  I had issues in the past with the Iridium's getting strange when boost is applied, they seem not to like the increase cylinder pressures over long distances.
Title: Re: One for the 250cc folk
Post by: generatorshovel on September 08, 2014, 08:43:10 AM
Wee bit lean. :wink:

Agree'd.

and keep an eye on those electrodes.  I had issues in the past with the Iridium's getting strange when boost is applied, they seem not to like the increase cylinder pressures over long distances.
Methanol
Title: Re: One for the 250cc folk
Post by: wobblywalrus on September 15, 2014, 11:35:42 PM
It might be worth it to do some research on plug type.  The high compression methanol motors I have seen did not use projecting tip plugs.
Title: Re: One for the 250cc folk
Post by: generatorshovel on September 16, 2014, 03:04:34 AM
Wee bit lean. :wink:

Agree'd.

and keep an eye on those electrodes.  I had issues in the past with the Iridium's getting strange when boost is applied, they seem not to like the increase cylinder pressures over long distances.


Agreed, I have new plugs on the way
It might be worth it to do some research on plug type.  The high compression methanol motors I have seen did not use projecting tip plugs.
(http://i156.photobucket.com/albums/t24/generatorshovel/all_zpsa3278c4f.jpg) (http://s156.photobucket.com/user/generatorshovel/media/all_zpsa3278c4f.jpg.html)

http://youtu.be/ZA7NEwX_kjk

Another test 'n ' tune today, still leanish,
Tiny
Title: Re: One for the 250cc folk
Post by: stay`tee on September 17, 2014, 06:27:50 AM
im seeing to much timing advance, needs a cuppla degrees less,,
Title: Re: One for the 250cc folk
Post by: generatorshovel on September 17, 2014, 06:52:03 AM
im seeing to much timing advance, needs a cuppla degrees less,,


Not an easy task Ronnie, 12 degrees static,ramping to and fixed at 47 btdc @ max hp, (15,000 rpm) dropping to 37 after.(not much info out there, took 3 yrs to find that info  :-o
To change, I need some more cubic dollars, and minisquirt, plus another lifetime to learn efi
Tiny
Title: Re: One for the 250cc folk
Post by: wobblywalrus on September 19, 2014, 11:36:49 PM
It might save a lot of time to set the jetting on a dyno and get traces of HP, torque, and mixture.  Advice I got this summer is to jet the engine to produce maximum torque.  Then, jet it to produce maximum power.  Then adjust the air jetting, emulsion tubes, etc so the same jets produce maximum torque and max HP.  His advice is to let the engine tell you the mixture it wants.
Title: Re: One for the 250cc folk
Post by: generatorshovel on September 20, 2014, 12:33:08 AM
Thanks Bo, unfortunately, I don't have access to a dyno , the closest is over 300 miles away, but I hear what you are saying mate.
I'm getting close, I just need to make the WOT a little safer, and get rid of the midrange miss (new plugs should do that), then I should be ready for a 3 mile run down the salt  :?
Tiny
Title: Re: One for the 250cc folk
Post by: wobblywalrus on September 20, 2014, 11:27:28 AM
Chapter 3 in David Vizard's "How to Build Horsepower" might have the info you need to get started on a fix.  The setup you are running now might be a good one after some adjustments.  This book is in print and reasonably priced.

 
Title: Re: One for the 250cc folk
Post by: RansomT on September 20, 2014, 09:11:48 PM
You know that is a "ton" of timing.  I don't know of any of the "modern" sport bikes that come close to 47 degrees... heck, a Gen 2 Busa is set to 34 BTDC from the factory.
Title: Re: One for the 250cc folk
Post by: generatorshovel on September 20, 2014, 10:01:39 PM
(http://i156.photobucket.com/albums/t24/generatorshovel/cbr250rr_advance_curve_hires_zps3d80bc8e.jpg) (http://s156.photobucket.com/user/generatorshovel/media/cbr250rr_advance_curve_hires_zps3d80bc8e.jpg.html)

Remember these little engines have a miniscule 32mm stroke, and spin like hair driers.
I cannot verify the chart is an accurate representation ?
Title: Re: One for the 250cc folk
Post by: maj on September 20, 2014, 10:36:23 PM
Tiny you need something like the Dyna  ARC2 that has a timing retard feature and much better spark
I am surprised your not killing the spark even now with that much cyl density
Title: Re: One for the 250cc folk
Post by: stay`tee on September 20, 2014, 11:07:38 PM
i run a Dyna ARC2 on the 12 and have been told that its good for 6-8 extra horsepower at peak,, on Methanol, with the spark restrike activated it cleans up the 1-4k range noticably,,

the retard function is 10* user activated,, had a button on the bars, on a pass at Bonneville i tried it at about 10k, the motor nosed right over, never used it anymore,,,
Title: Re: One for the 250cc folk
Post by: generatorshovel on September 22, 2014, 12:50:22 AM
Maj & Stay'tee, thanks for the tip(s)
I had a GREAT run today, NO MISS !, took it out to 17,000 in 1st thru 4th (remembered the button too)then short shifted into 6th and held it flat for 1/4 mile, did a plug chop & coasted to a stop collecting flies in my teeth.
(http://i156.photobucket.com/albums/t24/generatorshovel/one-four_zps0cc6c9c6.jpg) (http://s156.photobucket.com/user/generatorshovel/media/one-four_zps0cc6c9c6.jpg.html)

(http://i156.photobucket.com/albums/t24/generatorshovel/electrodes_zps9b6beb7f.jpg) (http://s156.photobucket.com/user/generatorshovel/media/electrodes_zps9b6beb7f.jpg.html)

http://youtu.be/5xLWzshRkwY      (MP3 sound file only)

Bo, Iv'e ordered that book, thanks mate

Remember, the ign timing this bike uses is unchanged from what it was sold with new, they usually burn ULP (gas), and NEVER ping
Considering methanol burns slower than gas, retarding the ign timing might make the time available for a burn ?
A once champion speedway outfit rider, Spotty Burke told me, ( despite his age his memory with his Triumph setup in 1956 remains as clear ), he ran 47 degrees btdc with methanol & beat a Vincent to gain the championship that year
Title: Re: One for the 250cc folk
Post by: maj on September 22, 2014, 04:18:49 AM
The only real positive way of figuring spark advance suitability to your setup is to retard it and see if power goes up or down
you could slot the crank pickup and maybe pickup a few degrees adjustment , but without a dyno or datalogging its a guessing game as the timing line on the sparkplug only gives you an basic indication

What plug gap are you running , looks like .035 (.8mm) or so , i would aim at much less

In 09 i tried methanol on the 750 and had to run what i considered a bit lean to get it to run clean throughout the range on a stock ign system, needless to say i burnt valves and head as the leaner mixtures gave me too much cyl temp
This Aussie season i hope to run it again if i can get everything together in time , and the first thing on the shopping list was a CDI ignition , that gave great spark energy for little power cost (counting my amps left for fuel pumps etc ) , before the Feb setback i had run high boost pressures cleanly at a very rich mixture , very promising , but its so rich the wideband is not reliable and will be backing it up with EGT when i get tuning again
Title: Re: One for the 250cc folk
Post by: generatorshovel on September 22, 2014, 05:14:10 AM

you could slot the crank pickup and maybe pickup a few degrees adjustment ,
Not really
(http://i1195.photobucket.com/albums/aa399/Blowncbr/chrispic.jpg) (http://s1195.photobucket.com/user/Blowncbr/media/chrispic.jpg.html)

What plug gap are you running , looks like .035 (.8mm) or so , i would aim at much less
Yep. out of the box 35 thou
 i had run high boost pressures cleanly at a very rich mixture , very promising , but its so rich the wideband is not reliable and will be backing it up with EGT when i get tuning again
On the previous run, A/F , although wrong ? was indicating 5.9 to 6.5
This run, it was hi sevens before the gauge freaked out and error coded, I'd gone from #620 main, to # 640, egt's were previously 1150, this run, 1050


I realize there are a zillion improvements that should / could be done to maximize the tune, but as this builds main purpose has been to keep me sane, and hasn't always been the case,,,,one slip will make it all worthwhile, especially if it's around 125, Iv'e been running since '96 & never gotten my 125 licence (Postie bikes tend to do that, Dave Plecas might have a chance on his though ?)

I'll fatten up the top end until it drowns, then work my way back from there (.22 thou plug gap next was the plan Greg)

Title: Re: One for the 250cc folk
Post by: wobblywalrus on September 22, 2014, 11:58:43 PM
In a few years when I retire I am going to drive ti A2 wind tunnel with the bike and rent a space at the local KOA for several days.  The bike will go into the tunnel, I will make some mods, and it will go back in until I get the aero sorted.  The I drive back home.  Maybe you could do this at the dyno shop?
Title: Re: One for the 250cc folk
Post by: Peter Jack on September 23, 2014, 01:24:51 AM
Why not go to the new tunnel in Salt Lake City? It's way closer and very similar.

Peter
Title: Re: One for the 250cc folk
Post by: TheBaron on September 23, 2014, 11:59:33 AM
I understand the trouble you are having tuning with methanol and the supercharger... It is not for the faint of heart, but you can do it if you understand most of the major issues....

Methanol burn rate is slower than gasoline (18% to 22%), so all else being equal, you need more spark advance so peak cylinder pressure occurs at the sweet spot of the power stroke (10 to 15 degrees atdc or so).

Boost pressurized fuel mix burns at a faster rate than normally aspired mixtures so you need less spark advance to get the cylinder pressure at the power stroke sweet spot....retard about 1 to 2 degrees per 5 psi boost is a good starting point

Yes, they tend to offset somewhat with the methanol burn rate being the major effect .

Boost mixtures become harder and harder to ignite due to the insulation effect of nitrogen gas, so spark plug gaps have to  go down.... .016" to .018" at very high boost or with a weak ignition system.....

Methanol will detonate when pushed to it thermal stability limit... It is about the equal of 116 octane gas when it is good ,,, a lot less when lean...

A/F GAUGES usually don't read accurately when methanol is rich,,, use the EGT instead.

Timing should be set for  "best continuous  torque" in the power band of the engine... Setting for the peak output using an inertia type dynamometer or short sprint runs has killed more endurance type racing engines than saints in heaven .... When one is WFO for more than a few seconds at a time,,, the tune must be turned down else killer detonation will occur...

A "Knock-Sensor" system would be your best friend in finalizing your tune....

Good luck and I'll continue following your efforts with interest....I have a air-cooled blown 350 pushrod motor that is also very tricky to tune....

Robert in California



Title: Re: One for the 250cc folk
Post by: generatorshovel on September 23, 2014, 06:07:07 PM
WOW ! Thank you kindly for sharing your experience & wisdom Robert.  :cheers:
Title: Re: One for the 250cc folk
Post by: Peter Jack on September 23, 2014, 06:19:52 PM
Sorry for the hijack a couple of posts back Tiny. My reply was to WobblyW about the wind tunnel and didn't pertain to your problem. If you had me working on that you'd likely be buying pistons by the bushel basket.  :-D :-D :-D

Pete
Title: Re: One for the 250cc folk
Post by: generatorshovel on September 23, 2014, 08:52:39 PM
In a few years when I retire I am going to drive ti A2 wind tunnel with the bike and rent a space at the local KOA for several days.  The bike will go into the tunnel, I will make some mods, and it will go back in until I get the aero sorted.  The I drive back home.  Maybe you could do this at the dyno shop?
Unfortunately Bo, our Prime minister keeps shifting the retirement goal posts, now the male retirement age in Oz is 67, or if you were born after the baby boom years, 70 .
This might be ok for someone like a politician, who has never don't a days hard physical day's work in their life, but the average working man has to abuse his body to earn play money, to do things like LSR,,,,,, :-o
I still have 6 and a bit years to go, so that option is out.
Sorry for the hijack a couple of posts back Tiny. My reply was to WobblyW about the wind tunnel and didn't pertain to your problem. If you had me working on that you'd likely be buying pistons by the bushel basket.  :-D :-D :-D

Pete
I realized this Pete, no problems with me


When I melted the piston in '13, I had gravity feed fuel (bad mistake) dirty plugs (which cleared)and a sort of lean midrange, and very fat main jetting, watch this video below, I think when the engine cleared just before hitting 5th gear, the engine was starting to starve for fuel

http://youtu.be/z_L8DsJis2o

This next pic os of the F1-11 dash during the last test run, the #4 egt is unreliable (poor 12v supply I cant find the reason for) although it is the hottest cylinder, 1 thru 3 are a close indication of the egt average temps

(http://i156.photobucket.com/albums/t24/generatorshovel/EGTs_zpsd6d22a18.jpg) (http://s156.photobucket.com/user/generatorshovel/media/EGTs_zpsd6d22a18.jpg.html)

When I was planning this rebuild, I decided, after believing the manufactures claim their gauges are suitable for "all" fuels, including alcohol, which should helped me set up the carb, but in fact, it thru me right off target (live & learn)

Thanks again for everyone's input
Title: Re: One for the 250cc folk
Post by: wobblywalrus on September 23, 2014, 11:19:06 PM
Tiny, those combustion chambers are real small and the plug is in the center of them.  The flame only travels a very short distance in comparison to the much larger chambers we are used to.  It may be, because of this, that the little Honda needs a lot less spark advance than we think it should have. 
Title: Re: One for the 250cc folk
Post by: TheBaron on September 24, 2014, 10:22:49 AM
Tiny,,, I have another possibility of the low EGT on the #4 cylinder....

When a cylinder is detonating, the EGT reading reads LOWER !!!

Why ? Because the amount of heat going into the exhaust is reduced as the heating of the combustion chamber and piston increases.
(there is only so much available after all). Detonation produces shock waves that destroy the insulating boundary layer of gas next to the parts so the heating of the parts increases greatly.

I'd test all the EGT probes and gauges with a common heat source to see what is what, but if #4 holed a piston I'd say that that EGT was reading correctly at that time...

Robert
Title: Re: One for the 250cc folk
Post by: RansomT on September 24, 2014, 10:47:13 AM
Do you have enough slack in the cable to switch #3 and #4 EGT sensors?   You can then see if it is a voltage issue.
Title: Re: One for the 250cc folk
Post by: generatorshovel on September 24, 2014, 06:38:41 PM
Tiny,,, I have another possibility of the low EGT on the #4 cylinder....

When a cylinder is detonating, the EGT reading reads LOWER !!!

Why ? Because the amount of heat going into the exhaust is reduced as the heating of the combustion chamber and piston increases.
(there is only so much available after all). Detonation produces shock waves that destroy the insulating boundary layer of gas next to the parts so the heating of the parts increases greatly.

I'd test all the EGT probes and gauges with a common heat source to see what is what, but if #4 holed a piston I'd say that that EGT was reading correctly at that time...

Robert

The swapping of leads was done with #1 & #2 a while back, all thermocouples were tested in the same boiling water pot, the chinese seem to have a problem with accuracy,,,,,,,

I don't take the EGT's as gospel, rather an indication changes have worked with jetting

Sometimes when I flick the ign s/w on, there is no reading with #4 until I tap the gauge  :-o
Ambient temps before engine start vary (sometimes #4 is also feint)

Do you have enough slack in the cable to switch #3 and #4 EGT sensors?   You can then see if it is a voltage issue.

Yes
Title: Re: One for the 250cc folk
Post by: generatorshovel on September 24, 2014, 06:50:04 PM

I'd test all the EGT probes and gauges with a common heat source to see what is what, but if #4 holed a piston I'd say that that EGT was reading correctly at that time...

Robert

There were no EGT figures available the year I melted the piston Robert, I had the idea they would slow me down if I looked at them (as happened in 2006 with my Postie bike,,1350degrees 1 mile before I reached the 1st timer), I backed off a bit , got the temp down to 1200 and got a time, fully how 3/4 throttle went as quick as WOT did,,lol
Title: Re: One for the 250cc folk
Post by: wobblywalrus on September 24, 2014, 09:49:19 PM
A knocklight sensor is attached to my cylinder block.  The light is right near the tachometer and it is on the dash just under where I look when I am going down the track.  It flickers red when there is any detonation.  That red light gets my attention quick.  It is easy to see.  It has paid for itself a hundred times by telling me if my fuel choice and advance curve are not compatible.

The sensor performance is simply related to piston diameter.  A racer on this site verified my sensor was correct for my piston diameter.  You need to do this 'cause of the little guys that are in your bike.  You will need a different sensor than the one supplied with the light.  It is for bigger pistons.  PM me if you want details.

Do not get discouraged.  Racers from all over the world are wanting you to succeed.     
Title: Re: One for the 250cc folk
Post by: generatorshovel on September 24, 2014, 10:05:22 PM
PM sent Bo
Title: Re: One for the 250cc folk
Post by: wobblywalrus on September 26, 2014, 12:45:42 AM
Tiny, here is the info on the knock light I use.  Some of these lights are pretty complicated with all sorts of adjustments and other mental stuff.  I wanted something real simple that I do not need to think about.  The light is the self calibrating one on www.knocklight.com/Knock-Light-Store.html (http://www.knocklight.com/Knock-Light-Store.html)

The little bracket is removed from the light and this water resistant case was made from copper water line tubing and fittings.  Normally it is tied to the fairing dash with zip ties.  Now it is zip tied to the handlebar.  We look at it during the dyno work and the fairing is not on the bike when this is done.

The light glows red during detonation, the occasional chain rattle, missed shifts, etc.  The mind quickly learns to filter all of this out and to focus on detonation.

The sensor is shown.  These are sensitive to different input frequencies and their selection is based on piston diameter and the desired harmonic.  It is best to discuss this with the manufacturer.  The sensor I use for pistons of almost 100mm dia would be deaf to the rattle of the little ones in the 250.

Hopefully this is the info you need. 
Title: Re: One for the 250cc folk
Post by: wobblywalrus on September 26, 2014, 01:02:02 AM
Just read the new knock light topic.  The sensor is attached to the side of the cylinders by a stud.  It is real close to the source of detonation shock waves.  Maybe that is why the light works well.
Title: Re: One for the 250cc folk
Post by: generatorshovel on September 26, 2014, 07:54:23 AM
Thanks for sharing Bo
Title: Re: One for the 250cc folk
Post by: generatorshovel on October 24, 2014, 06:44:34 AM
I think I'm ready for 2015,, managed 121 with under control EGT's, plugs look ok, a tad darker on the fire ring with #680 mains, compared to #640 mains, not textbook discolouration, but "safe"
http://youtu.be/oNbWwK05phQ
It will be interesting to see how far it'll wind out in 6th ?
Title: Re: One for the 250cc folk
Post by: wobblywalrus on October 24, 2014, 10:26:40 PM
That looks like Burt Munro's test road in Nevada according to the movie.  The bike sounds good.
Title: Re: One for the 250cc folk
Post by: Old Scrambler on October 25, 2014, 07:58:21 PM
Tiny...........Great to hear the news :cheers:

You have an interesting challenge and have been getting some great advice...............Hopefully you will GO FAST :-) :-)
Title: Re: One for the 250cc folk
Post by: generatorshovel on October 26, 2014, 05:44:29 PM
Thanks Dennis, Bo, apart from the help I've received from the  Landracing, & DLRA forums, This wonderful thing called the internet has made research possible (I wouldn't say easy) , Kudos to those folk who pioneered this, and many other forms of motorsport, without this luxury we now take for granted.
Title: Re: One for the 250cc folk
Post by: generatorshovel on November 13, 2014, 10:13:46 AM
Sorry for the hijack a couple of posts back Tiny. My reply was to WobblyW about the wind tunnel and didn't pertain to your problem. If you had me working on that you'd likely be buying pistons by the bushel basket.  :-D :-D :-D

Pete
Your wind tunnel mention made me smile Pete, does a test run into a 40 mph head wind achieve the same result ?, if so, bin there done that, ha ha ha.
I have 12 spare pistons mate, just in case, ( not sure if they will still be available if I need more, these took over 12 months to track down)
Tiny
Title: Re: One for the 250cc folk
Post by: wobblywalrus on April 04, 2015, 12:10:00 AM
Congratulations.  It looks like you set a record, or at least made a nice run.   
Title: Re: One for the 250cc folk
Post by: generatorshovel on April 04, 2015, 12:27:01 AM
Congratulations.  It looks like you set a record, or at least made a nice run.  
Thanks Bo
One for you
http://www.pipeburn.com/home/2015/04/04/the-triumph-salt-racer.html#.VR9q1-EYOwc

Onerun Tiny
Title: Re: One for the 250cc folk
Post by: Peter Jack on April 04, 2015, 12:31:18 AM
OUCH!!!  :x :x :x
Looks like you only have 11 spare pistons now.
Sorry to hear that.

Pete
Title: Re: One for the 250cc folk
Post by: generatorshovel on April 04, 2015, 12:36:08 AM
Problem #1 , 5th gear (have 6)
Problem #2  popped a coolant hose
Result, loose exhaust valve seat due to excessive heat = carnage.
I found the valve head in the sump, aluminum sludge got thru the oil filter, cooked a main bearing, the head is totalled (have a spare, and 2 intake, 2 ex valves ,new in the shed, and 8X.5 mm o/s spare pistons)
  :cheers:
Tiny
Title: Re: One for the 250cc folk
Post by: Peter Jack on April 04, 2015, 01:13:20 AM
Can the head be welded up as a spare? I've repaired some pretty badly damaged heads and they've lived to fight another day.  :-D :-D :-D

Pete
Title: Re: One for the 250cc folk
Post by: generatorshovel on April 04, 2015, 01:27:30 AM
Can the head be welded up as a spare? I've repaired some pretty badly damaged heads and they've lived to fight another day.  :-D :-D :-D

Pete
I doubt it Pete, I have a few spares .
The run was nearly aborted before it began, Dodge Honda cdi, even though I have a huge Harley battery,( no spark below 11.7 Volts) the day was cool, the pilot, midrange jetting was fat, I couldn't get it fired until the lakester before me left the line, so my mojo was gone,,,when I hit 16,000 revs, (thought I was in top) I was happier than the 1st time butterflies blew out my arse, thinking I was knocking on 130's door, how wrong can ya be,,lol, I even went the full mile wot, which told me a few things, boost dropped to 10 (from 12) @ 16,200 and it wasn't gonna go any faster, max HP is at 16,000, blower seemed maxed out (revs) and carb is a tad too small, one day, I'll know if it likes my top gear gearing ?
I lost 8 mph on the salt compared to asphalt testing.
https://youtu.be/8bGxSJAc8Io
Tiny
Title: Re: One for the 250cc folk
Post by: fordboy628 on April 04, 2015, 06:46:25 AM
Can the head be welded up as a spare? I've repaired some pretty badly damaged heads and they've lived to fight another day.  :-D :-D :-D

Pete

Hi Tiny,

Is the cam drive setup a gear drive?    Do the cams ride directly in the head, without bearings?    If so, don't bother repairing the head.    You would need to weld the whole head face, and it is most likely to warp the head some.    You would need to re-machine the whole head.

If the cams are chain drive or belt drive, skimming the head after welding one chamber becomes possible.    If there is a separate cam carrier, so much the better.

I've repaired dozens of BD and Lotus heads by welding, always successful.    Wasn't easy or cheap, but it was cost effective compared to the price of a new head.

As you have other heads available, the smart and cheapest move is to put the damaged one in the shed, for the day when no undamaged heads are available.   Just start over with a fresh casting.

Sorry about your result.
 :cheers:
Fordboy
Title: Re: One for the 250cc folk
Post by: Peter Jack on April 04, 2015, 09:12:47 AM
I didn't say it would be easy or cheap!!!!  :cry: :cry: :cry: :evil:

Pete
Title: Re: One for the 250cc folk
Post by: generatorshovel on April 04, 2015, 04:33:50 PM
Can the head be welded up as a spare? I've repaired some pretty badly damaged heads and they've lived to fight another day.  :-D :-D :-D

Pete

Hi Tiny,

Is the cam drive setup a gear drive? YES   Do the cams ride directly in the head,YES without bearings?   
As you have other heads available, the smart and cheapest move is to put the damaged one in the shed, for the day when no undamaged heads are available.   Just start over with a fresh casting.

Sorry about your result.
 :cheers:
Fordboy
Thanks for your input Fordboy , I just need a longer shelf to store the growing stack of dead bits now .
Lucky for me, when I stumbled across the new valves I installed prior to this years Speedweek, the guy had 20 of each @ the right price, so I bought 'em all  :-D
Murphy's law tells me that the main bearing shell(s) I need are the size that won't be available .
Tiny
Title: Re: One for the 250cc folk
Post by: Hoody on April 05, 2015, 03:08:34 AM
Can the head be welded up as a spare? I've repaired some pretty badly damaged heads and they've lived to fight another day.  :-D :-D :-D

Pete

Hi Tiny,

Is the cam drive setup a gear drive? YES   Do the cams ride directly in the head,YES without bearings?   
As you have other heads available, the smart and cheapest move is to put the damaged one in the shed, for the day when no undamaged heads are available.   Just start over with a fresh casting.

Sorry about your result.
 :cheers:
Fordboy
Thanks for your input Fordboy , I just need a longer shelf to store the growing stack of dead bits now .
Lucky for me, when I stumbled across the new valves I installed prior to this years Speedweek, the guy had 20 of each @ the right price, so I bought 'em all  :-D
Murphy's law tells me that the main bearing shell(s) I need are the size that won't be available .
Tiny

If you can't find the parts in Aus take a look on this site https://www.davidsilverspares.co.uk/ (https://www.davidsilverspares.co.uk/)  He often holds spares for old Hondas.
Title: Re: One for the 250cc folk
Post by: generatorshovel on April 05, 2015, 07:46:16 AM
Thanks Hoody, I was aware of David Silvers, as it turns out, they are the only ones saying one bearing shell size (13226-KY1-000) might become available, all others say 'discontinued" item, I managed to get the other sets from DIY spares also in the UK.
I will get an email from gaybay & DIY, should the last 'rod shell pair come out of a closet somewhere ?
Title: Re: One for the 250cc folk
Post by: wobblywalrus on April 06, 2015, 01:10:34 AM
An alternative is to contact Carillo here in the US and to describe your problem.  They can build you a set of rods for available big end shells.  Then, the crank journals need to be resized to fit the shells.  It is expensive, but it is a way to go if nothing else works.   
Title: Re: One for the 250cc folk
Post by: fordboy628 on April 06, 2015, 10:47:34 AM
An alternative is to contact Carillo here in the US and to describe your problem.  They can build you a set of rods for available big end shells.  Then, the crank journals need to be resized to fit the shells.  It is expensive, but it is a way to go if nothing else works.   

Yes it is.   And perhaps the only way forward at some point in time.

I find myself doing it more and more these days as bearing stocks become depleted for "older" (read that unprofitable) product lines.    And then there is the issue of a "race quality" bearing, an even rarer duck for "older" product lines.

"Why are you beating your head against the concrete wall daddy?"      "Because it feels so good when I stop . . . . . ."

 :dhorse: :dhorse: :dhorse:

 :cheers:
Fordboy
Title: Re: One for the 250cc folk
Post by: generatorshovel on April 06, 2015, 07:25:55 PM
I went down the Carrillo road with the 175 single Bo, that bike may get finished when I repair the 250.
Fordboy, since stripping the crankcases and checking oil galleries for reasons the main bearing shell failed (no damage to the journal), I found none, clean as a babies bottom.
When setting up the piston oilers I fitted an aux. oil pump, just to feed the squirters, but after testing I decided that the aux pump would not be needed,,,I guess that decision was wrong.
(http://i1195.photobucket.com/albums/aa399/Blowncbr/AuxOilPump0006_zps6e50437b.jpg) (http://s1195.photobucket.com/user/Blowncbr/media/AuxOilPump0006_zps6e50437b.jpg.html)
Pressure dropped from 70 psi, to 50 psi when the squirters were activated( something else I forgot to do during the run), the pistons survived without oil cooling.
I have found most of the bearing shells I need, with exception of one rod set for the replacement rod (the damaged cylinder's rod now has some slight twists in it).
The head took the brunt of the force, sparing the crankshaft from visible damage.
This bike has the same financial limits all of my projects have, keeping fun as the 1st priority, and doing the best I can, given the realistic goals I have.
Throwing cubic dollars into the engine might lift the bar, but until I sort the setup I have, or some fool wants to waste some sponsorship dollars on it, I'll use the KISS method.
A boost increase to 20 psi might not hurt (much) after all, Dave Plecas has boosted his stock bottom ended CT110 to 45 psi, without failure,,yet (111 mph in 2014)
Tiny
Title: Re: One for the 250cc folk
Post by: fordboy628 on April 06, 2015, 09:35:14 PM
Tiny,

It is usually how a crank is drilled that dictates the pressure required in use.    It is possible that this setup requires 70 psi (or higher) for adequate oil flow to prevent contact/damage.

Since the general rule of thumb is 10 psi per 1000 rpm, it seems to me to be a "lower" oil pressure system, with 70 psi at the bottom of the reliable range.

Honda did lots of work in the 60's & 70's in an effort to gain power output by reducing "parasite drag" and parasitic power losses.    It does work, but it cuts the margin to component failure to the absolute minimum.

Problems can arise when you don't know the minimums . . . . . .    And, as you are aware, destructive testing can be expensive.    Although there is no arguing about the finality of the results.

 :cheers:
Fordboy
Title: Re: One for the 250cc folk
Post by: wobblywalrus on April 06, 2015, 10:19:49 PM
The Carillo rods can be ordered as "top loaders" so the big end shells can be checked or changed from the cylinder side of the motor.
Title: Re: One for the 250cc folk
Post by: generatorshovel on July 31, 2015, 11:27:35 AM
Bo, these engines have the barrels as part of the upper crankcase half, pistons & rods have to go in from the top, no access to "upside down" bolt access  :x

I'm finally ready to re-assemble the engine, when the weather  warms a bit, using the only bigend shells available, Chinese   :roll: , actually, they are well made, and within standard specs, with +.25 mm available, but these would require a crank re-grind.

Main bearing shells were available from Honda, once I got over the "do not sell outside of Japan" hurdle , as it turns out, the later model MC22 engines shared the same main journal size, but with more sizes available (in .006 mm graduations)

I have been talked into entering the Boca Bearing comp again, and would appreciate a vote or 2 if anyone hase the inclination to do so (votes need to be verified via email 1st, but you won't get spammed by doing so)
http://www.bocabearings.com/innovation-contest/ContestantDetails.aspx?ProjectID=197

July voting is almost finished, but votes can be done  monthly ( I might get a free tee)
Tiny
Title: Re: One for the 250cc folk
Post by: generatorshovel on September 29, 2015, 06:19:13 AM
Here's another thought provoking post , Fordboy, as usual will have good advice,,
I'm in the process of rebuilding, with another head (pentroof 4 valve) which, after having .4mm skimmed off to flatten it, results in contact 'tween head/piston
I have yet to figure the best way of measuring the clearance I had, with the last head, but that too had been skimmed, and I feel it was so close to having a similar piston/head collision, although I have not found any evidence this happened.
These engines have a 33.8 mm stroke, 49.5 mm bore X 4
According to this
http://www.mssholdings.co.uk/documents/1812_1368456939_Performance-Bikes-Article.pdf
The CBR250/4's suffer
12,000 rpm .013" 'rod stretch
16,500     .023"   "     "
18,000     .0235"  "     "
So, by adding .0235"(stretch @ 18,000rpm) to .02362"(desired minimum clearance) = 0.0706"

(0.00119 mm) I will know how thick my head gasket needs to be.
The fun bit is to measure the clearance I have (less than ZER0), and had (the last head was .4mm

fatter(.0157")
Tiny
Title: Re: One for the 250cc folk
Post by: fordboy628 on September 29, 2015, 10:05:02 AM
Here's another thought provoking post , Fordboy, as usual will have good advice,,
I'm in the process of rebuilding, with another head (pentroof 4 valve) which, after having .4mm skimmed off to flatten it, results in contact 'tween head/piston
I have yet to figure the best way of measuring the clearance I had, with the last head, but that too had been skimmed, and I feel it was so close to having a similar piston/head collision, although I have not found any evidence this happened.
These engines have a 33.8 mm stroke, 49.5 mm bore X 4
According to this
http://www.mssholdings.co.uk/documents/1812_1368456939_Performance-Bikes-Article.pdf
The CBR250/4's suffer
12,000 rpm .013" 'rod stretch
16,500     .023"   "     "
18,000     .0235"  "     "
So, by adding .0235"(stretch @ 18,000rpm) to .02362"(desired minimum clearance) = 0.0706"

(0.00119 mm) I will know how thick my head gasket needs to be.
The fun bit is to measure the clearance I have (less than ZER0), and had (the last head was .4mm

fatter(.0157")
Tiny


Tiny,

Where is the contact located?    On the flats?   Or is there contact in the "pent roof" area?

How did you get a .0706" total from .0235" + .02362" ?    I get .04712".   Is there something left out of the math?


When confronted with this situation, I usually find "zero" by using feeler gauges/head gaskets to raise the head on the block.   The tricky bit is to find "zero".

It never hurts to err on the "plus" side by a small amount.

How much piston "rockover" at TDC overlap do you anticipate?   I'd measure the rockover in a cold bore just to get a number.   You might be surprised at how much there is and you might want to increase your piston to head minimum clearance.   Check it to be sure.

 :cheers:
Fordboy
Title: Re: One for the 250cc folk
Post by: generatorshovel on September 29, 2015, 04:53:18 PM
Fordboy. thanks for your help (again) Contact is just in the areas shown in the pic , (on all 4  cyl's)
Math was not one of my favorites at school .
(http://i156.photobucket.com/albums/t24/generatorshovel/aaaaaaaaaapiston%20mods%20005%20copy_zps2m9hjmoh.jpg) (http://s156.photobucket.com/user/generatorshovel/media/aaaaaaaaaapiston%20mods%20005%20copy_zps2m9hjmoh.jpg.html)
Rockover has not been measured, only "looked at" and is considerable, but won't be a problem as the collision area is parallel to the pins,
In hindsight (laying in bed thinking last night) after removing the head face, the tapered area in the combustion chamber (where the collisions occur) has changed shape(shortened due to taper), I should also check the squish clearance with the "old" head too,
I'm thinking, the engine was fine with a 1.6 mm head gasket before .4 mm was shaved off the bottom on the "new" head, this would work, so if I get a new gasket made @ 2mm, things "should be" ok , but thinking is not proving I guess ?

Edit >>>>
(http://i156.photobucket.com/albums/t24/generatorshovel/AaaaaaaassEmbly_zpsl2hlq3xu.jpg) (http://s156.photobucket.com/user/generatorshovel/media/AaaaaaaassEmbly_zpsl2hlq3xu.jpg.html)
This pic shows the contact areas on the pistons

Tiny
Title: Re: One for the 250cc folk
Post by: generatorshovel on September 30, 2015, 02:12:08 AM
I didn't get the time to Adobie & upload the piston contact pic before going to work this morning, the above pics will help explain where the contact is made (all 4 cylinders)
Tiny
Title: Re: One for the 250cc folk
Post by: wobblywalrus on September 30, 2015, 09:13:57 PM
Cometic here in the US is good at making copper gaskets for custom applications.  They might be a help if none can be made in AUS.
Title: Re: One for the 250cc folk
Post by: bones on September 30, 2015, 11:49:32 PM
Hey Tiny
   You say you skimmed  0.4mm off the head to make it flat
  Did you need to remove the full amount to Just clean it up?
  Are the cam tunnels now bent but you have a flat head surface?

  Maybe try to fit the head and the cams to see if they spin ok

 cheers   Bones
Title: Re: One for the 250cc folk
Post by: generatorshovel on October 01, 2015, 01:38:17 AM
Cometic here in the US is good at making copper gaskets for custom applications.  They might be a help if none can be made in AUS.
Bo, I'll use the "almost local" firm who made the last one, I was more than happy with it, thanks anyway .
Title: Re: One for the 250cc folk
Post by: generatorshovel on October 01, 2015, 01:52:06 AM
Hey Tiny
   You say you skimmed  0.4mm off the head to make it flat
  Did you need to remove the full amount to Just clean it up?
  Are the cam tunnels now bent but you have a flat head surface?

  Maybe try to fit the head and the cams to see if they spin ok

 cheers   Bones
Bones, it was ok crossways, from 1 to 4, but needed the .4 mm removed to flatten the area of the gear drive area that "pokes out"
Most 250/4 heads need a skim for the same reason.
I worked out the piston(s) just touched in the areas marked in the previous post pic, which meant, seeing this head is skinnier than the previous by .3mm (not .4 as 1st measured roughly) and once checked (checked, not relying on my memory this time) meant even when I raced this year, I didn't have enough clearance, although no piston/valve contact was evident (except for #3 , which ate a valve & valve seat)
She'll be apples with a 1.6mm gasket .
I had another problem too, cam drive gears tend not to enjoy being forced together as a result of the head skim (not adjustable)
(http://i156.photobucket.com/albums/t24/generatorshovel/dohc%20cam%20gear%20drive_zpswxqqelc1.jpg) (http://s156.photobucket.com/user/generatorshovel/media/dohc%20cam%20gear%20drive_zpswxqqelc1.jpg.html)
Title: Re: One for the 250cc folk
Post by: fordboy628 on October 02, 2015, 10:06:09 AM
Fordboy. thanks for your help (again) Contact is just in the areas shown in the pic , (on all 4  cyl's)
Math was not one of my favorites at school .
(http://i156.photobucket.com/albums/t24/generatorshovel/aaaaaaaaaapiston%20mods%20005%20copy_zps2m9hjmoh.jpg) (http://s156.photobucket.com/user/generatorshovel/media/aaaaaaaaaapiston%20mods%20005%20copy_zps2m9hjmoh.jpg.html)
Rockover has not been measured, only "looked at" and is considerable, but won't be a problem as the collision area is parallel to the pins,
In hindsight (laying in bed thinking last night) after removing the head face, the tapered area in the combustion chamber (where the collisions occur) has changed shape(shortened due to taper), I should also check the squish clearance with the "old" head too,
I'm thinking, the engine was fine with a 1.6 mm head gasket before .4 mm was shaved off the bottom on the "new" head, this would work, so if I get a new gasket made @ 2mm, things "should be" ok , but thinking is not proving I guess ?

Edit >>>>
(http://i156.photobucket.com/albums/t24/generatorshovel/AaaaaaaassEmbly_zpsl2hlq3xu.jpg) (http://s156.photobucket.com/user/generatorshovel/media/AaaaaaaassEmbly_zpsl2hlq3xu.jpg.html)
This pic shows the contact areas on the pistons

Tiny

Tiny,

There are 4 choices for fixing your "interference" problem.    I'll add some thoughts/comments:

1)   Hand fettle the piston domes.      NOT RECOMMENDED, too subject to variations.

2)   Machine the piston domes in/with a fixture.      ALSO NOT RECOMMENDED. Honda bike pistons I've seen all have "hollow" domes, you don't want to get too thin in cross section.

3)   Hand fettle the interference points in the chambers.    Acceptable, but a lot of checking and cc'ing to "equalize".

4)   Machine the interference points in the chambers with a fixture.    BEST, and most accurate.   Also, biggest PITA*.   Still need to check and cc, etc.

Regardless of which solution you choose, seems like the head becomes a slight "one off" unit, pretty common with hand built race engines.

Pick your poison . . . . .
 :cheers:
Fordboy
Title: Re: One for the 250cc folk
Post by: generatorshovel on October 02, 2015, 12:32:41 PM
Option 5 is my choice,
 A 2 mm head gasket will give me .0354" clearance (same as with head #1) which is more than enough to allow for rod stretch / crank flex past the operating rpm
I may have to remove some alloy beneath the 3rd cam gear and shim the cassette to suit , this is also a PITTA as the gear is a "scissor" split type , spring loaded,(to quieten the gear train), this makes measuring the gear fit difficult, but if I spread the "scissor" gear to line up the teeth, clamp it, then measure the lash I should be ok ?
Title: Re: One for the 250cc folk
Post by: edinlr on October 02, 2015, 01:47:02 PM
If you are having gear drive issues, then I think option #5 is your only way to go.  Otherwise you need to calculate your compression with the thicker head gasket and try to determine if cleaning up the piston or the head may help preserve some compression.  After all the hard work you don't want to go and lose a couple points of compression if you can avoid it.  It looks like with the interference on the piston being on the sides under the pin, that you should have plenty of material to take off a touch to help your clearances.  I have done tons of pistons by hand in the old days, but I would probably have someone mill off the material to be more precise.  You also should contact your piston supplier to see what they say too.  Last, with those floating cylinders, I am guessing you will always have problems getting a good seal especially with the rpm you pull.  I am thinking JimL used to try to get 3 or 4 runs between having to replace gaskets on his CX race bike.
Title: Re: One for the 250cc folk
Post by: generatorshovel on October 02, 2015, 04:29:52 PM
If you are having gear drive issues, then I think option #5 is your only way to go.  Otherwise you need to calculate your compression with the thicker head gasket and try to determine if cleaning up the piston or the head may help preserve some compression.  After all the hard work you don't want to go and lose a couple points of compression if you can avoid it.  It looks like with the interference on the piston being on the sides under the pin, that you should have plenty of material to take off a touch to help your clearances.  I have done tons of pistons by hand in the old days, but I would probably have someone mill off the material to be more precise.  You also should contact your piston supplier to see what they say too.  Last, with those floating cylinders, I am guessing you will always have problems getting a good seal especially with the rpm you pull.  I am thinking JimL used to try to get 3 or 4 runs between having to replace gaskets on his CX race bike.
The gear clearance is only a problem after skimming the head, compression point losses are advantageous, given the engine is supercharged, these pistons have had the crown peaks removed  and the peaks are now @ the level of the original spark plug indents.
If you want to upset piston suppliers, just ask them to forge 49.5mm custom pistons, they don't really want to know, and price accordingly , the cheapest quote was $500 each, bare !
The copper gasket that is being used up until now has survived 2 engine disasters, 2 official runs, & over 50 hard miles with no leakage, all with between 10 & 15 LB boost.
There is no easy way to modify these ladies wrist watches, that Ive found (yet)
Title: Re: One for the 250cc folk
Post by: fordboy628 on October 02, 2015, 04:51:03 PM
Option 5 is my choice,
 A 2 mm head gasket will give me .0354" clearance (same as with head #1) which is more than enough to allow for rod stretch / crank flex past the operating rpm
I may have to remove some alloy beneath the 3rd cam gear and shim the cassette to suit , this is also a PITTA as the gear is a "scissor" split type , spring loaded,(to quieten the gear train), this makes measuring the gear fit difficult, but if I spread the "scissor" gear to line up the teeth, clamp it, then measure the lash I should be ok ?

Man I HATE it when there is no way to "adjust" the lash in gear drives.    Lack of adjustments requires VERY tight tolerances for the parts.

What the factory is really doing is:  Making the parts throwaways when they are "out of spec".   Expensive.   And when the design is no longer serviced for replacement parts, well . . . . . . . . .

You are right.  Option 5 is the only choice.

 :cheers:
Fordboy
Title: Re: One for the 250cc folk
Post by: generatorshovel on January 05, 2016, 11:46:48 PM
https://youtu.be/BF9HBG9bvng

https://vimeo.com/150402046

Are we there yet ?  :-D
Title: Re: One for the 250cc folk
Post by: fordboy628 on January 06, 2016, 04:47:33 AM
Nice.

Your shed (?) looks kinda like my garage.

I presume you are off to the lake this year.    Best of luck to your efforts.

 :cheers: :cheers: :cheers:
Fordboy
Title: Re: One for the 250cc folk
Post by: generatorshovel on January 06, 2016, 04:34:37 PM
Nice.

Your shed (?) looks kinda like my garage.

I presume you are off to the lake this year.    Best of luck to your efforts.

 :cheers: :cheers: :cheers:
Fordboy
I have history, working myself into a different corner of the shed  :-) each year, this is the 1st tine I've been close to the kitchen sink.
I hope you are as good at cleanup as you are with engines Fordboy ?
 I still rent space in forwards backwards land apparently, I managed to drop a 4mm grub screw into the blower (retrieved) , neglected to disassemble the Holley needle & seat assembly on the Mikuni fuel carb mods , it flooded, sneakingly, which was the reason for the difficult starts, then,,the salt got into another grub screw in the blower drive extension shaft  , when is tight, not tight in the right places ?,,when the top belt pulley & shaft try to part company from the blower (luckily the cover was off,  I wasn't riding, & it was idling, so I had time to kill it before any damage was done),,that's today's job .
 Runnin' outa time,,,,,,,,,,,,, :-o
Title: Re: One for the 250cc folk
Post by: wobblywalrus on January 07, 2016, 09:32:56 PM
Tiny, this is extremely Mickey Mouse, but it works...sometimes.  The method is to put bluing dye on your gears and to see exactly where they interference occurs.  You are lucky sometimes and it is at the tip of the teeth where they fit in the valley of the other gear's teeth.  In this case, the offending male gear can be put in a lathe and the tops of the teeth skimmed off just enough to get a clearance fit.  Keep in mind that the aluminum engine parts that support the gear train expand more with heat than the gears.  The gear-to-gear clearance will increase when the engine heats up, so being a bit tight when cold might not be as big of an issue as one thinks.  Another Mickey Mouse solution is to make a 50-50 mix of Comet or Bon-Ami and grease and to use this to lap in the offending gears.  Sometimes this is all that is needed to do the job.  The hardening layer on Honda gears is sorta minimally thin so this method should not be used to remove more than a few thousandths of an inch at most.   
Title: Re: One for the 250cc folk
Post by: generatorshovel on January 08, 2016, 12:02:05 AM
Thanks Bo,,Iv'e been a bit busy lately, I should have posted a followup regarding my clearance issues,,
  I found the problem, ME !
Under (almost) every head bolt, there is a copper washer,,,what I neglected to remember was that the bolt directly under the gear cassette does not use a copper washer,
To really throw me, one tooth on the idler gear is 3 poofteenths higher than the rest (who says Japan make quality stuff?), and it just happened to nudge the head bolt @ TDC, Once I removed the washer, like the good book said (in Japanese) , problem solved  :roll:
I now have a spare 1.6mm copper head gasket, so I can not worry too much about skimming the head next time  :lol:
Title: Re: One for the 250cc folk
Post by: fordboy628 on January 08, 2016, 07:33:20 AM
Nice.

Your shed (?) looks kinda like my garage.

I presume you are off to the lake this year.    Best of luck to your efforts.

 :cheers: :cheers: :cheers:
Fordboy

I hope you are as good at cleanup as you are with engines Fordboy ?


Ahhh, sort of.    The wife's car still won't fit in the workshop (she still insists it is HER garage . . . . . .) so that's a bi-annual "issue".     Can't complain too much though, overall she is a keeper.

 :cheers:
F/B
Title: Re: One for the 250cc folk
Post by: Seldom Seen Slim on January 08, 2016, 08:08:22 AM
Tiny said:  "...one tooth on the idler gear is 3 poofteenths higher than the rest..."

Poofteenth?  Good word.  Must be from your neck of the woods -- haven't heard that one before.  Now - if you'd said that it was "3 RCHs proud..."  I woulda knowed whatcher sayin'.
Title: Re: One for the 250cc folk
Post by: Speed Limit 1000 on January 08, 2016, 08:30:13 AM
RCH?
Title: Re: One for the 250cc folk
Post by: Seldom Seen Slim on January 08, 2016, 08:38:01 AM
Aw, c'mon, Johnboy.  You're telling me that you've never heard of that very small yet precise measurement?  Nah, I don' believe it. :-D
Title: Re: One for the 250cc folk
Post by: jacksoni on January 08, 2016, 08:49:56 AM
Aw, c'mon, Johnboy.  You're telling me that you've never heard of that very small yet precise measurement?  Nah, I don' believe it. :-D
And then there is the even smaller precise measurement- a flat one...... :cheers:
Title: Re: One for the 250cc folk
Post by: Speed Limit 1000 on January 08, 2016, 11:53:57 AM
A red one :-D Just wanted to see what you would say. I had to explane that to a female captain when I was in the Air Force. The colonal was surprized when I told her it was a unit of radar measurement.
Title: Re: One for the 250cc folk
Post by: aussievetteracer on January 13, 2016, 06:03:59 AM
One of my (very) old timers is "foreskin of a fly's di*k- just a whisker.
Denis
Title: Re: One for the 250cc folk
Post by: tauruck on January 14, 2016, 11:40:03 AM
At least it's not a d$%K in a shirtsleeve?. :-D
Title: Re: One for the 250cc folk
Post by: generatorshovel on April 07, 2016, 09:59:01 PM
The horse is not yet completely dead,,but needs resuscitation, again,,,
The engine didn't enjoy a feed of Teflon, but most if it parked itself against #4 cyl intake valves, which seems to have contributed to the heat build up in that cylinder, it didn't help that, in my rush to leave for the salt trip , forgot the correct carby slide, the one that was in it had been trimmed to lean off the gas (post methanol use) mixture.
(http://i156.photobucket.com/albums/t24/generatorshovel/rotor2_zpswhzzg8hx.jpg) (http://s156.photobucket.com/user/generatorshovel/media/rotor2_zpswhzzg8hx.jpg.html)
Maximum blower rpm is 11,250 (15,000 engine rpm)
(http://i156.photobucket.com/albums/t24/generatorshovel/case_zpsj64qhzmh.jpg) (http://s156.photobucket.com/user/generatorshovel/media/case_zpsj64qhzmh.jpg.html)
(http://i156.photobucket.com/albums/t24/generatorshovel/dents_zps5bdniogt.jpg) (http://s156.photobucket.com/user/generatorshovel/media/dents_zps5bdniogt.jpg.html)
My extremely meager race budget does not allow for coughing up over $3,000 to get custom forged pistons, and I know I'm really wasting my time using cast krap, but they have "sorta" worked in the past,,,with 10 lb boost, so I'll go back to 5 to 8 lb, reuse the stock cams (lots of overlap) , and rev the Krap out of it again next (my last attempt with this one) year
Title: Re: One for the 250cc folk
Post by: wobblywalrus on April 08, 2016, 12:23:26 AM
Is there a black or dark brown stain from oxidized oil at the centers of those pistons on the undersides of the crowns?  Can you show close up pictures of any problem areas on the pistons?
Title: Re: One for the 250cc folk
Post by: generatorshovel on April 16, 2016, 07:46:46 PM
I haven't looked yet Bo, I'll leave the pistons on their individual rods 'till the new pistons return from the ceramic crown treatment, less chance of mixing 'em up that way  :roll:
The failure had many  contributing factors, hotter plugs, wrong carb slide,power jet isolated etc. , I thought it strange the egt's didn't get over the high 800's (f) :? , although I wasn't riding it & can only rely on the video and feedback from a rider who has very little seat time on the bike.
 I'll go back to the "safe" tune I used last year, back the boost off a tad, cooler plugs, slightly richer (than last year) mixture using the power valve in an attempt to do the timer trip trick, in top gear, and with water wetta in the system, not just air,,,, :-o
Boost can always be increased when needed, on the salt.
Tiny
Title: Re: One for the 250cc folk
Post by: wobblywalrus on April 17, 2016, 12:55:56 AM
The ceramic treatment was what I was going to suggest if the oxidation on the underside indicates the center of the crowns are getting hot.  It seems that you are doing this.
Title: Re: One for the 250cc folk
Post by: generatorshovel on April 27, 2016, 03:31:33 AM
Here you go Bo,,,

Title: Re: One for the 250cc folk
Post by: wobblywalrus on April 28, 2016, 01:18:23 AM
There are shiny areas on the upper skirts on the outer pistons just below the rings.  Does careful examination indicate those two got hotter and expanded more than the two inner ones?
Title: Re: One for the 250cc folk
Post by: generatorshovel on April 28, 2016, 05:33:49 AM
The black areas is  a Molybdenum Disulfide DF1 coating Bo, it wears off real quick,,,,
#2 piston has only done 6 miles work, mostly at full noise, the others have had 2 years worth of abuse( 10 miles?) :-D
Title: Re: One for the 250cc folk
Post by: wobblywalrus on April 28, 2016, 08:57:21 PM
Sometimes the ignition trigger coils or the ignition triggers on the flywheel are out of alignment.  This affects the timing curve of either the two inner or the two outer cylinders.  It looks like only one is having problems is that outer one so that cannot be an issue.

Many times I used cast pistons in applications where forged would be proper.  One problem with the cast ones was the lack of thermal conductivity on the crown and this resulted in hot spots.  The ceramic coatings will help with this, I am told.

Sometimes that problem is seen on the cylinder whose carb is furthest from the fuel supply.  It starves for gas first 'cause it sucks hind tit, as folks say.  It goes lean and the piston crown melts.  As I recall, there is a single Weber or Holley for all four cylinders.  This probably is not the problem.

The only thing I can think of is fuel condensation.  The fuel is condensing on something and it flows along the walls of the inlet tract to some cylinders but not all.  Or, it condenses and revaporizes in a way that gives that end cylinder a lean mix.   
Title: Re: One for the 250cc folk
Post by: generatorshovel on October 02, 2016, 08:10:40 PM
I'm slack with updates, sorry,,,,
Most of my problems this year were a result of a very poor valve seat job, plus some impregnated alloy in the valve faces, the problem was cured by doing the job properly, myself,,A job not made any easier by the valve seat dia being smaller than the smallest Neway cutters, but , as usual, they were modified to do the job.
Another problem reared it's ugly head when putting the "stock" cams in, in an attempt to detune the setup a tad, these cams have 1mm more intake lift, the problem I now have, is .001" less piston/ valve clearance than I have lift, this took some research & careful measuring, and I discovered the pistons I am using have .96 mm higher domes,,,,,than stock
Measure twice eh !  :roll:
Tiny
Title: Re: One for the 250cc folk
Post by: wobblywalrus on October 02, 2016, 08:35:10 PM
The same thing happened to me when preparing the Triumph for Pendine.  Some late night work with an angle grinder on the piston crowns did the trick.  The valve pockets were deepened in the pistons.  It takes a pint or three to calm the mind and steady the hand before that sort of precision work.
Title: Re: One for the 250cc folk
Post by: generatorshovel on November 03, 2016, 07:25:40 PM
It seems I'm the only person to ever try to repair these bike(ette) engines , EVERYTHING needs to be special order, even to machine the minuscule 16.5mm exh valve seats (3.5mm valve stems)
 :dhorse:
Tiny
Title: Re: One for the 250cc folk
Post by: wobblywalrus on November 04, 2016, 12:39:23 AM
On the Triumph, these are modified stock:  cylinder head and crank.  These are special order:  rods, crank and rod bearings, pistons, rings, and pins, cylinders, head and base gaskets, valve seats, valves, springs, guides, keepers, tappet buckets, valves, cams, cam gears, clutch plates, clutch springs, ignition module, coils, spark plugs, exhaust system, intake manifolds, carbs, and air filters.  Sometimes I wonder why it is called a Triumph on the entry sheet.  "Mongrel" would be a better description.  Do not feel like you are alone on this matter.   
Title: Re: One for the 250cc folk
Post by: generatorshovel on November 04, 2016, 02:24:09 AM
I don't mind the challenge of finding the "right" parts Bo. but the waiting for them to be made & delivered sure frustrates the hell outa me,  my hates also include deadlines, and being forced to try to "compromise", as it usually leads to failure.
 Why is a good,cheap build idea always transformed into a 5 year expensive addiction ? has stubbornness got anything to do with it ?
Tiny