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Author Topic: It`s it`s The Ballerum Blitz. Room for another Beeza?  (Read 18293 times)
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Rasmussen
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« Reply #15 on: February 22, 2014, 02:51:04 AM »

Thanks WW. It feels good to get a positive response on something I felt a bit awkward posting smiley
 
Tom: believe you`re right about the cases breathing through the timing side. Unfortunately I only took one picture with the engine apart, and that only shows a bunch of parts spread out. Regret not taking a lot now, it might just have been possible to see something. if I don`t get something figured out before, it`ll be on my to do list next time it`s disassembled.

Tiny: from the noise that thing of yours produce I`d guess you`re really close to getting there grin
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Rasmussen
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« Reply #16 on: February 22, 2014, 04:17:51 AM »

Well, back to the build smiley
Have spent quite some time lately testing on the backroads. The bike is surprisingly well behaved, starts first kick almost every time. Idles fine, and feels "right". My main issue has been a large power drop when shifting into fourth. I get a significant drop in RPM, and unfortunately run out of road long before Im able to pick up the revvs again. No doubt  of it leaning out at WOT.
My first thought was (what I understand almost all are struggling with) to little flow to the fuel bowl.
First measurements showed a measly 0,2 liters of flow per minute. Realised that with my setup there may be a need to keep the tank full to get enough flow, and I had only filled in a couple of liters (or half a gallon). A full tank got me to 0,5 l/m, a huge difference.
Next couple of runs showed a (very) slight improvement, but still far from good enough. Went crazy on the mainjet going from 160 to a gigantic (and silly) 210 in a couple of steps, but still had a leanout sad
Drastic steps where called for:

I really, really hated doing this! knowing all to well I was going to mess up an otherwise fine carb I drilled the inlet from 4 to 5 mm`s. Just had to be sure, and have a couple of carbs in spare. The idea was simply to test, and if finally getting it rich enough, mess with making/finding a suitable float/needle setup later.
Took off with fuel spraying out the overflow, but still, a leanout in high gear shocked bummer!

It suddenly dawned on me, that maybe my carb was too large (38 mm Keihin butterfly). It makes sense (to me at least). Up to third I may be running on the pilot jet at a moderate throttle opening giving me a good vacuum signal in the venturi to draw the fuel. Shifted into fourth, hammering the throttle, my high gearing (got a very widespread "trials" gearing) drops RPM on both engine and of course blower enough to loose a lot of vacuum in the venturi combined with a fully open throttlevalve.

Next logic step:

A Keihin CV borrowed from my shovelhead. Larger at 40 mm, but being a CV should help keeping my airflow, and thus vacuum at WOT.
First tests have shown a huge improvement. Im able to go full bore, and still have the bike accelerate albeit a bit slowly.
Still think I need a smaller carb, so got these yesterday:

A row of 36 mm Mikuni CV`s taken from a FJ 1200 Yamaha. It should be possible to get at least one good carb out of this, and leave me with enough spares to experiment. This will be my project for this weekend.

Where I`m at now

Still way to lean. Would one of you in the know please have a look at the "firing ring" (what`s the right expression?) marked with the red arrow. Got a feeling I may run a bit too advanced. It should be in the middle of the bend on the side electrode, not?. Comments on this, the look of the plug in general, and everything else will be greatly appreciated smiley

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stay`tee
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« Reply #17 on: February 22, 2014, 04:32:16 AM »

yes, the optumin point for the ignition timing is in/on the middle of the bend,, smiley
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Rasmussen
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« Reply #18 on: February 22, 2014, 04:54:37 AM »

Thanks ST smiley Then should I advance or retard to move the line to where it should be? my gutfeeling says retard, which is probably also the safest thing to do smiley

Completely forgot, you may be able to answer this also: the hole just above the "made in Japan" marking. What`s that for? I was thinking maybe a vacuumline for the fueltap? should I just plug it?
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stay`tee
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« Reply #19 on: February 23, 2014, 12:18:26 AM »

go with your gut feeling, the thing needs retarding, wink,

not sure what the hole in the carby is for,, if its the vacume for the fuel tap, wont hurt to just plug it,, smiley
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wobblywalrus
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« Reply #20 on: February 23, 2014, 11:31:21 PM »

A vacuum gauge hooked up to a hose on the intake manifold helps when you are learning how to use big carbs.  The goal is to open them slowly enough to maintain the intake vacuum.  Sometimes it is awkward to wait long enough to get the carb open and maintain vacuum during the opening process.  The track is too short, etc.  This is a sign the carb is too big, as you have figured out.

The best carb size, in my experience, is the smallest one that will provide adequate atomization at peak horsepower.  How many rear wheel HP is your goal? 
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Rasmussen
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« Reply #21 on: February 24, 2014, 11:59:41 AM »

Stay Tee: thanks a lot, retarded it will be  smiley

WW: A vacuumgauge! Now that is a brilliant idea. Don't know why I didn't think of that. Thanks for suggesting it. The more I think about it, the more sense it makes. I mean, I could be jetting from now on until hell freezes over, but if I for some reason (blowerpulses?) have a positive pressure spike there's no way I'm getting fuel into the manifold. I'm sure you mean the largest carb that still gives good atomization smiley. That sounds like good advice.

Have spent the weekend messing with my new (old) 36 mm Mikuni CV. It only had a 1,5 mm inlet to the fuelbowl. Got it up to 3,8 using a needlevalve from a flatslide carb. Took a lot of fiddling, but got it to work. Don't really feel comfortable with it though. Somehow I don't really trust it to keep on working properly, it being quite used and with a heavily modified float and needlevalve. Took a quick decision, and ordered a Keihin CV like the one I have had the best results with. It did actually work, and hooking up a vacuumgauge, rolling on the throttle slowly, and enlarging the jets I believe it should be possible to (finally) get it right.

Now if all else fails grin:

Inspired by the mentioning of a Wal Phillips fuel injector on Generatorshovels build diary, I just had to try. Yes I know it's turned the wrong way, but that saved me from turning a flange. Believe it or not, it actually started and ran with this! Just for a few seconds, and I didn't dare to take it out for a ride, with this primitive setup, but it just maybe could work.
Hope to have my new carb this week, and if the weather holds up, take the bike out with retarded ignition and a vacuumgauge smiley

Almost forgot, targeted HP: not really any specific target. It's got (a claimed) 18 stock, so there should be room for improvement. I'd say anything above 30 would be satisfactory. 35 would be fantastic:-)
« Last Edit: February 24, 2014, 12:05:21 PM by Rasmussen » Logged
wobblywalrus
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« Reply #22 on: February 24, 2014, 10:45:39 PM »

Adjust your float level as per manufacturer's recommendations for pump gasoline.  Connect a clear piece of fuel line tubing to a hose barb on the float bowl drain screw.  Route the hose up alongside the float bowl with the hose end open.  Open the fuel supply and let the float bowl fill with pump gasoline.  The fuel level you see in the hose will be the level in the bowl.  Make a scratch mark on the side of the float bowl.

Drain the gas and put in your race fuel.  Do the same thing and look at the fuel level.  Fuels that are heavier than pump gas will show a low level.  The floats float higher in them and they shut the valve off too soon.  You will need to readjust your floats upward so the fuel level in the bowl is the same as with pump gas.  Use the mark you made earlier.  The opposite is true if your fuel is lighter than pump gas.

Look at the fuel level in the hose alongside your bowl during your dyno work.  It should not drop significantly.  There is a fuel delivery problem if it does.

35 hp needs a 34 through 40 mm carb based on my old carb chart.  40mm would be about right for a carb with a butterfly and 34 or 35mm with a slide carb.

Baron's Speed Shop in London has a lot of experience with Amal carbs in race applications.  Amal makes special parts for all sorts of racing fuels and applications.  An advantage to the animal carbs is it is bonehead simple to jet.  The monobloc is my favorite.  Every jet in the thing is easy to get at including the insides of the float bowl.   

 
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Rasmussen
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« Reply #23 on: March 02, 2014, 08:41:43 AM »

Not much progress here. Blame it on work and foul weather sad
WW: Going to put my trust in your chart and go with the 40 CV smiley. Got mixed emotions about the Amals. What little experience I have with them have been with the MK2 (the one with the black plastic lid) and it wasn`t all good. Really think I should settle on the CV, and make it work instead of keeping on messing around and wasting precious time. Really comforting to know your chart says I`m in the ballpark though.

While waiting for the weather to clear up, I thought some of you may find these thermographic images I did interesting. Especially those of you working on or considering a blower.
Please note that these are taken in cold damp weather, and after a very short (1/2 mile) run. Almost as far from Bonneville conditions as you can possibly get. Actual temperatures should not be taken to seriously, considering this. Instead focus should be on the temperatures relative to one another. The text is my interpretation of what is going on, some of you may disagree, in which case it would be really interesting to know what you make of it smiley

Overall view, shows no major worries. Mostly interested in the exhaust here. No major restrictions. A returning heatwawe clashing with an outgoing one would have shown as a hot spot.

The very good atomization provided by the CV helps in keeping the runner from carb to blower very cold. This is actually colder than ambient, and feels cold to the touch.

The blower itself, as expected, gets hot. But (what surprised me the most)

when expanding into the plenum, it cools considerably again. Not nearly as bad as feared grin

Unexpected find. My pop off valve leaks, running a calculated 8-10 PSI, and with the valve set at approx 30. Blowback? if so it`s completely undetectable when running. Pulses having the valve bounce on the seat sounds more likely. A richer mixture and a retarded ignition setting may help. At least that`s what I hope for. Doesn`t seem to affect running though, and could maybe just be disregarded if not too bad.

Unexpected finding #2. Beltwhip makes the belt hit the guard. It has to move nearly an inch for this to happen? Should be an easy fix, but nice to find out this early, and something I probably wouldn`t have discovered otherwise before the belt was ruined.
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saltwheels262
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« Reply #24 on: March 02, 2014, 10:22:42 AM »

that's a lot of good info gained from those thermal pictures.

will be interesting to know why there are leaks at the blow off valve.

any damage to the belt ?
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bub '07 - 140.293 a/pg   120" crate street mill  
bub '10 - 158.100  sweetooth gear
lta  7/11 -163.389  7/17/11; 3 run avg.-162.450
ohio -    - 185.076 w/#684      
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'16 -- 0 runs ; 0 events -- made a 2 state change in ZIP codes

" it's not as easy as it looks. "
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Scottie J
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« Reply #25 on: March 02, 2014, 10:49:57 AM »

That's awesome!  Where does one buy a thermal camera?  I can see how this information can be very useful, like the fact you were able to detect a blow off leak and the belt slapping the guard, both of which would be undetectable to the naked eye.  Very cool stuff!    cool

As for the Amal MK2.....  NOT a fan.  I have a brand new 930 on my '58 RE/Indian and it is a PITA to say the least.  Problems that I've noticed with it are:  There are NO external vents for the carb and it tends to vapor lock under heavy acceleration if you don't have both fuel feeds turned on.  If you leave the bike parked in the sun, the fuel will actually cook out of the bowl and cause the float to stick closed, making it a big PITA to get fuel back into the carb.  And the tunability is sub-par at best.  I've tried several different jets, needles, and slide cut-aways and I've NEVER been able to turn out the air-screw more than 3/4 to a full turn out before it stalls.  Seriously, the air-screw is usually at maybe 3/8 of a turn out.  I really REALLY wish I had just spent my money on a Mikuni.  The Amal will be getting replaced this summer and probably go up on Ebay.

Scottie J
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« Reply #26 on: March 02, 2014, 11:20:51 AM »

There are vents on Mk2s, they are the small hose fittings high up on the carb body.
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Scottie J
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« Reply #27 on: March 02, 2014, 11:23:35 AM »

I think the only actual vent on MY carb is in the body and exits into the air filter.  All I know is mine is barely a year old and has been giving me problems since I put it on.

Scottie J
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Andy Cooke
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« Reply #28 on: March 02, 2014, 01:08:38 PM »

Be extremely careful using IR cameras to measure temperature, it's a complicated science but some basics are:

IR cameras do not measure temperature <- if you remember nothing else, remember this.

IR cameras measure infra red, what they 'see' depends upon the target temperature and the 'emissivity' of the material.

The simplest way to get good IR temperature measurements is to paint everything with black stove paint, you will then get sensible results.

You will never get good IR temperature measurements from shiny stuff.

a list of emissivities of some materials http://www.engineeringtoolbox.com/emissivity-coefficients-d_447.html

Your camera will be calibrated to measure the temperature of a 'black body', this is an object with an emissivity of 1 (practically this is 0.98).  You probably have software that will allow you to adjust for the emissivity of the object you're looking at, this is very laborious in reality.  There is another sting in the tail, anything that isn't emissivity is reflectivity, so a black body has no reflectivity, and an object with emissivity 0.2 has a reflectivity of 0.8.  What this means is when you look at something with low emissivity the majority of what you measure may well be something hot being reflected in the surface.

You can't see infra red, things that look black aren't necessarily black bodies.

IR cameras are a great tool, but so often I see them being used badly, and to jump to poor conclusions.

Andy
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manta22
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« Reply #29 on: March 02, 2014, 02:05:58 PM »

Amen, Andy.

Regards, Neil  Tucson, AZ
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Regards, Neil  Tucson, AZ
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