Author Topic: One for the 250cc folk  (Read 101350 times)

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Offline generatorshovel

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Re: One for the 250cc folk
« Reply #75 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"

Tiny
Tiny (in OZ)
I would prefer to make horsepower, rather than buy, or hya it, regardless of the difficulties involved , as it would then be MINE

Offline generatorshovel

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Re: One for the 250cc folk
« Reply #76 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:
Tiny (in OZ)
I would prefer to make horsepower, rather than buy, or hya it, regardless of the difficulties involved , as it would then be MINE

Offline Stainless1

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Re: One for the 250cc folk
« Reply #77 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.
Stainless
Red Hat 228.039, 2001, 65ci, Bockscar Lakester #1000 with a little N2O

Offline Queeziryder

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Re: One for the 250cc folk
« Reply #78 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:
Old enough to know better, but too interested in speed to care

Offline maj

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Re: One for the 250cc folk
« Reply #79 on: March 09, 2013, 03:49:41 PM »
couple of custom sets coming from John for our 750's too  :cheers:

Offline generatorshovel

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Re: One for the 250cc folk
« Reply #80 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
Tiny (in OZ)
I would prefer to make horsepower, rather than buy, or hya it, regardless of the difficulties involved , as it would then be MINE

Offline Old Scrambler

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Re: One for the 250cc folk
« Reply #81 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.
2011 AMA Record - 250cc M-PG TRIUMPH Tiger Cub - 82.5 mph
2013 AMA Record - 250cc MPS-PG TRIUMPH Tiger Cub - 88.7 mph
2018 AMA Record - 750cc M-CG HONDA CB750 sohc - 136.6 mph
2018 AMA Record - 750cc MPS-CG HONDA CB750 sohc - 143.005 mph
2018 AMA Record - 750cc M-CF HONDA CB750 sohc - 139.85 mph
2018 AMA Record - 750cc MPS-CF HONDA CB750 sohc - 144.2025 mph

Chassis Builder / Tuner: Dave Murre

Offline generatorshovel

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Re: One for the 250cc folk
« Reply #82 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. "
Tiny (in OZ)
I would prefer to make horsepower, rather than buy, or hya it, regardless of the difficulties involved , as it would then be MINE

Offline Dr Goggles

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Re: One for the 250cc folk
« Reply #83 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........
Few understand what I'm trying to do but they vastly outnumber those who understand why...................

http://thespiritofsunshine.blogspot.com/

Current Australian E/GL record holder at 215.041mph

THE LUCKIEST MAN IN SLOW BUSINESS.

Offline generatorshovel

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Re: One for the 250cc folk
« Reply #84 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



« Last Edit: July 29, 2013, 04:12:04 AM by generatorshovel »
Tiny (in OZ)
I would prefer to make horsepower, rather than buy, or hya it, regardless of the difficulties involved , as it would then be MINE

Offline generatorshovel

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Re: One for the 250cc folk
« Reply #85 on: July 29, 2013, 04:05:24 AM »
More pics




« Last Edit: July 29, 2013, 04:13:09 AM by generatorshovel »
Tiny (in OZ)
I would prefer to make horsepower, rather than buy, or hya it, regardless of the difficulties involved , as it would then be MINE

Offline generatorshovel

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Re: One for the 250cc folk
« Reply #86 on: July 29, 2013, 04:09:33 AM »




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
« Last Edit: July 29, 2013, 04:15:06 AM by generatorshovel »
Tiny (in OZ)
I would prefer to make horsepower, rather than buy, or hya it, regardless of the difficulties involved , as it would then be MINE

Offline maj

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Re: One for the 250cc folk
« Reply #87 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 

Offline generatorshovel

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Re: One for the 250cc folk
« Reply #88 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
« Last Edit: July 29, 2013, 05:04:48 AM by generatorshovel »
Tiny (in OZ)
I would prefer to make horsepower, rather than buy, or hya it, regardless of the difficulties involved , as it would then be MINE

Offline Jon

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Re: One for the 250cc folk
« Reply #89 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
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