yyz Posted April 30, 2006 Report Posted April 30, 2006 hey all, am having problems on my right carb... the carb bowl overfills and fuel will bubble slightly out of the overflow drain but not drain completely, then the cylinder loses fire but only at rpm's just under the powerband... the carb acts like it is air locked because it doesn't seem to drain on it's own and it acts like it isn't pulling fuel from that main jet... jets are not clogged, switched floats, needles and seats left to right, bowls are correct left/right, same thing... right side carb overfills... have to pull over into neutral and rev to clean out the excess fuel... it just starting doing this on a new build... ran these same carbs all last year on my mid-port with no problems. running 410 main jets (fat for break-in), toomey needles 5th clip, 25 pilots 1 1/2 out, vforce2 reeds, k&n clamp-ons, full drag port with boosts, cpi inframes, noss head 19cc domes, .020 over pro-lites, trued/welded crank, stock timing, 50/50 citgo 110/amoco 91 w/32:1 Super M, 150psi both cylinders at 2400ft. any suggestions?... i pulled my other carbs from my mid-port and re-jetted and will try that tomorrow... i am thinking i might have a plugged circuit (choke circuit maybe) in the carb itself. thanx, yyz Quote
batoutofshell Posted April 30, 2006 Report Posted April 30, 2006 hey all, am having problems on my right carb... the carb bowl overfills and fuel will bubble slightly out of the overflow drain but not drain completely, then the cylinder loses fire but only at rpm's just under the powerband... the carb acts like it is air locked because it doesn't seem to drain on it's own and it acts like it isn't pulling fuel from that main jet... jets are not clogged, switched floats, needles and seats left to right, bowls are correct left/right, same thing... right side carb overfills... have to pull over into neutral and rev to clean out the excess fuel... it just starting doing this on a new build... ran these same carbs all last year on my mid-port with no problems. running 410 main jets (fat for break-in), toomey needles 5th clip, 25 pilots 1 1/2 out, vforce2 reeds, k&n clamp-ons, full drag port with boosts, cpi inframes, noss head 19cc domes, .020 over pro-lites, trued/welded crank, stock timing, 50/50 citgo 110/amoco 91 w/32:1 Super M, 150psi both cylinders at 2400ft. any suggestions?... i pulled my other carbs from my mid-port and re-jetted and will try that tomorrow... i am thinking i might have a plugged circuit (choke circuit maybe) in the carb itself. thanx, yyz 509827[/snapback] 410 jets if thats true( I didn't think they made them) theres your problem right there Quote
pipebomb Posted April 30, 2006 Report Posted April 30, 2006 (edited) yeah just might be. you could drive a damn bus through those. For VM, TM and TMX Mikunis they run right up to 720's. Edited April 30, 2006 by pipebomb Quote
80overShee Posted April 30, 2006 Report Posted April 30, 2006 wow....410's are HUGE. My mods are in my sig and I run 320's. VF's and port work jumps it 10 jet sizes? You might be a little small on that pilot there. You are fat on the needle and fat on the main, seems odd you run stock pilot. Quote
yyz Posted April 30, 2006 Author Report Posted April 30, 2006 410 jets if thats true( I didn't think they made them) theres your problem right there 509840[/snapback] yeah... that's true... the left side is fine with it's 410, just the right has the problem... once broke in, i will go down to a 390 or 400, the needle will stay where it is at... last year i ran my mid-port all season with the same exact setup only with 340 mains... made 65hp on pump fuel with t5's at little sahara, ok. my engine builder's porting is very good... this drag port is loading the cylinders hard... reminds me of nhra super stockers... lots of cam with fat carburation. we found it odd too that a 25 pilot was working... on the 4mil drag port we also just had done, we had to go to a 27.5 pilot... right now it is nearly broke in and it has 390 mains, same needle 5th clip, cpi inframes, rk tech head w/ stroker domes, vforce3's, same fuel and mix as this one... it screams. i will keep researching... thanx... yyz Quote
yyz Posted May 1, 2006 Author Report Posted May 1, 2006 (edited) ok... setup a different set of carbs the same (with 410's)... now all is good... was a damn windy day here, about 55 degrees... no plastics on the bike... good thing i had the 410's... i wouldn't want to be much leaner. still don't know what is wrong with the other carb... might just need an ultrasound. any suggestions??? (other than telling me my jets are too big) yyz Edited May 1, 2006 by yyz Quote
batoutofshell Posted May 1, 2006 Report Posted May 1, 2006 I was just saying you are the only person Ive heard heard on here that uses bigger then 330 and there are alot of ""drag"" bikes on here with more mods than you have Quote
yyz Posted May 1, 2006 Author Report Posted May 1, 2006 I was just saying you are the only person Ive heard heard on here that uses bigger then 330 and there are alot of ""drag"" bikes on here with more mods than you have 510264[/snapback] well that is probably true to a degree... more mods yes, but what mods?... bigger carbs?... in that case, my big jets would be a mute point (these are stock carbs)... a stroker?... strokers usually require slightly leaner jetting given all else is equal (they generally pull more fuel through the same size hole as a non-stroker)... more compression on straight race gas?... should be loading the cylinders hard in that case. they do make jets for the vm series all the way up to 720... in super stock nhra drag racing the class allows for any valve train and intake, but stock carb(s) are required with any jetting desirable... point is on stock carbs with big camming (porting in this case)... fat is good. like i said, last year my mid-port dynoed at 65 hp in little sahara, ok. on pump fuel with 340 mains... 65.01 to be exact and this was in september... little sahara is about 1000 ft.... i generally do run slightly on the rich side, but then i also get at least two seasons out of my top ends as well... still has 128psi both cylinders, had 130 april '05 after break-in and i raced the shit out of that bike last year... some weekends at least 100 or more runs on the sand. one might think too that maybe i would have an air leak if i am having to jet so rich, but both plugs are evenly colored, coffee creamer brown with a tinge of dark brown... just right for break-in... will more than likely drop back to a 390 or 400 after that. it's all good... not trying to argue, just trying to fix my carb issue. yyz Quote
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