Yamahopper10 Posted November 4, 2010 Report Share Posted November 4, 2010 (edited) Ok.. so ive just switched my banshee from 110 race fuel to alcohol.. Im having trouble tuning the carbs. I put on 38mm mikunis bored to 39, and converted to alky with the power jets.. It will start up ONLY with the chokes on, and it revs very high so I have to shut it off immediatly, and it will die if I give it any throttle. What could cause this? Pilot jets, needles? Too lean? I know its impossible to jet someone elses bike over the internet, but any info would be greatly appreciated. I know a decent amount of stuff about carbs Im just not 100% familliar with tuning yet. I have my air screws 1/2 turn out. Also, I could be wrong, but Im not too worried about being rich for now, because alky will still run if its rich correct? Ive had people tell me to take it in and have it tuned, but Im going to need to know how to do it by myself at some point anyways. Thanks guys.. Oh and by the way, Its a stock stroke, aggressive drag ported, with cut head... Edited November 4, 2010 by Yamahopper10 Quote Link to comment Share on other sites More sharing options...
Wildcardracing Posted November 4, 2010 Report Share Posted November 4, 2010 What size are your dumps and mains drilled out to? If the dump tubes are too small it can cause the kinds of issues you're describing. What pilots and needles? What is your elevation? Sounds like you are lean for sure. Your pilot circuit will enrichen as you turn your air screws in. Should start tuning with the power jets open all the way, but you're not drawing on them in the lower rpms. There is a great writup on atvdragracers on how to read alky plugs that will help you with tuning once you get this issue addressed. Quote Link to comment Share on other sites More sharing options...
tripledsracing Posted November 5, 2010 Report Share Posted November 5, 2010 yea i agree sounds like the dump tube is to small..on my 4mil stck cyl ive got my dumps and mains 116 and clip in middle with a 52 pilot and is tuned in perfect..my powerjets 1 turnout from closed,when its chilli out side 2 turns out..air screw is at 1 1/2 turns..my elevation is 1000..hope this helps.. Quote Link to comment Share on other sites More sharing options...
Yamahopper10 Posted November 7, 2010 Author Report Share Posted November 7, 2010 Ha i got it figured out. I had adjusted my throttle cable way out when i put the new carbs on and never adjusted it back, so the slides were about 1/8th of the way open, causing it to rev up. Also my air fuel screws were way in. But now ive got 116 dump tubes with 116 mains (both drilled out) and my air screws are 2 1/2 turns out, power jets are 2 1/2 turns open and its running pretty good. Cant wait to go run it and see how it does on alky once i get it fine tuned. Quote Link to comment Share on other sites More sharing options...
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