blackedout96 Posted June 7, 2010 Report Share Posted June 7, 2010 I recently switched from 34mm PJ gassers to 34 PJ alky carbs. The bike ran flawlessly on the gas carbs, right down to the hour that I pulled them off. I made all the necessary changes, plugs, gas cap, etc. I start the bike up and it just revs to the sky, pull the kill switch and it still goes to the verge of blowing up!! My first thought is detonation from an air leak, but it was perfect before I switched the carbs. Any thoughts on this would be greatly appreciated! -Mike Quote Link to comment Share on other sites More sharing options...
shanYE west Posted June 7, 2010 Report Share Posted June 7, 2010 I recently switched from 34mm PJ gassers to 34 PJ alky carbs. The bike ran flawlessly on the gas carbs, right down to the hour that I pulled them off. I made all the necessary changes, plugs, gas cap, etc. I start the bike up and it just revs to the sky, pull the kill switch and it still goes to the verge of blowing up!! My first thought is detonation from an air leak, but it was perfect before I switched the carbs. Any thoughts on this would be greatly appreciated! -Mike Its lean. Could be a number of different things. What jetting did you start with? Quote Link to comment Share on other sites More sharing options...
AWR Posted June 7, 2010 Report Share Posted June 7, 2010 dump tubes too small Quote Link to comment Share on other sites More sharing options...
Onesickcrewcab Posted June 7, 2010 Report Share Posted June 7, 2010 What size did you drill your dump tubes and main jet? What kind of powerjet did you install? Quote Link to comment Share on other sites More sharing options...
tundish2800 Posted June 7, 2010 Report Share Posted June 7, 2010 I have 34 pj on alky. Drilled the dump to 125, main at 118, and pilot of 62. and dont have any problems. I would say you should have at least a 120 dump with a 116 main to start, Pilots jet would say to start around a 52 or 55. Quote Link to comment Share on other sites More sharing options...
sheefreak Posted June 7, 2010 Report Share Posted June 7, 2010 Won't have anything to do w/your PJ and not much to do w/your dump tube/needle. On my alky carbs, I drop the needle all the way down and don't have runaways. Pilot jet and airscrews.....where they at? Quote Link to comment Share on other sites More sharing options...
blackedout96 Posted June 7, 2010 Author Report Share Posted June 7, 2010 (edited) Carbs are setup as follows.... .118 Mains, .118 dumps, EGL needles(I'll have to check where the clip is on the needles), 68 pilots, K&T Power Jets. I know the pilots are stupid fat, I'm going to change them but it's not something that would cause this problem. *Air screws are 1 1/4 out Edited June 7, 2010 by blackedout96 Quote Link to comment Share on other sites More sharing options...
sheefreak Posted June 7, 2010 Report Share Posted June 7, 2010 You should be fine w/that fat of a pilot. Are you sure you didn't have a slide that was hung open, or the slides set too high? Quote Link to comment Share on other sites More sharing options...
blackedout96 Posted June 7, 2010 Author Report Share Posted June 7, 2010 Yep, the slides are seating perfectly. First thing I checked was to see if one of them had hung open but it didn't. I'm going to raise the needles as far as they go, maybe drill the dumps to .120 and see if that doesn't do it. If not, it has to be an air leak. Just blows my mind that it could be that, have about 2 hours on the fresh build and it was running absolutely perfect when I pulled the gas carbs off. Stranger things have happened though I guess. Thanks for all the advise everyone, I'll keep you updated! Quote Link to comment Share on other sites More sharing options...
firebanshee Posted June 8, 2010 Report Share Posted June 8, 2010 I think you should be good with the .120 on the dumps.My track carbs are drilled to .120 and my dune carbs are drilled to .122 Quote Link to comment Share on other sites More sharing options...
Paul M Posted June 8, 2010 Report Share Posted June 8, 2010 (edited) Try a leak down test but it seems like a lean hang to me ! Next time it does that , Nail the throttle wide open and that should kill the motor , I know it dont sound right but thats what I was taught by a top builder! and it worked for me . Edited June 8, 2010 by Paul M Quote Link to comment Share on other sites More sharing options...
blackedout96 Posted June 8, 2010 Author Report Share Posted June 8, 2010 Thanks HQ brothers for all the advice. I have it torn down for a leak down right now. If it tests good, ill be doin some hoggin on the carbs. I usually just jam it into gear to kill it when this shit happens, scares me to open the carbs when its already trying to blow its self up. Ill try it though. Sheefreak, ill prolly see u at the dunes or wmsd. I ride with JD. Thanks for your thoughts Man! Quote Link to comment Share on other sites More sharing options...
blackedout96 Posted June 8, 2010 Author Report Share Posted June 8, 2010 All I have is a Stock stroke A&S dune port, that's why I thought .118 on the dumps & mains would be fine. i'll see what the leak down tells me.... Quote Link to comment Share on other sites More sharing options...
badassbanshee479 Posted June 9, 2010 Report Share Posted June 9, 2010 turn the choke nobs in till they stop turning..... the pj's use the choke nob as the idle adjustment. if they are to far out the engine will lean rev like your talking. also try and get your slides down as far as you can so if it does run away all ya do is let off the throttle and it should kill the motor. Quote Link to comment Share on other sites More sharing options...
gregrob Posted June 9, 2010 Report Share Posted June 9, 2010 The dump tubes are too small. Trust me, I've had the same exact problem. You need to drill the dump tubes to at least .122 even if you dont plan on running that big of a main jet. The needle is plugging off too much of the dump with it at .118 and causing it to run away. Drill them to .122 and it will purr like a kitten Quote Link to comment Share on other sites More sharing options...
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