bry Posted June 8, 2009 Report Posted June 8, 2009 have a 421 with 34pjs 52 pilots 155 mains cel needle in the middle clip k&n pods vf3s 15 tooth front gear and 40 rear and it bogs bad off the line is it the carbs or just a POS>?? acts like it doesnt have the power to get out of its own way!! need help i have tried from 45-55 pilots and the same reaction. Quote
Paul M Posted June 8, 2009 Report Posted June 8, 2009 (edited) sounds like its a pos man lol j/K ! well what type of surface are u racing on how much do you wieght are you starting in 1st or 2nd ? really unless u way 120lbs imo you are way over geared all your jetting sounds real close , I would drop 1 in the front or slap a 43 rear sprocket on there and see what happens! Edited June 8, 2009 by Paul M Quote
bry Posted June 8, 2009 Author Report Posted June 8, 2009 sounds like its a pos man lol j/K ! well what type of surface are u racing on how much do you wieght are you starting in 1st or 2nd ? really unless u way 120lbs imo you are way over geared all your jetting sounds real close , I would slap a 23 rear sprocket on there and see what happens! i run on a med-hard dirt i am 135lbs in second gear first is just to low..not good launching in first. also running a 20 inch kenda tire. Quote
Paul M Posted June 8, 2009 Report Posted June 8, 2009 (edited) yeah you want to be set up to start in 2nd ! thats what I would do try messing with the gearing the cheapest way would be to drop 1 in the front Edited June 8, 2009 by Paul M Quote
dajogejr Posted June 8, 2009 Report Posted June 8, 2009 How does the machine pull after that? Has it been leak down tested? All the ignition components checked out? A properly setup 4 mil cub should pull that gear with a 135 lb rider...go to a 42 tooth rear. If that doesn't fix it...you need to look elsewhere. I don't know if CEL are a good needle for PJs, I did use them in my 421 and it ran great with 35PWKs. Quote
RadarRacing Posted June 8, 2009 Report Posted June 8, 2009 IMO it's gearing mostly but I think a 155 might be slightly rich just look at your plugs. I think a 15/40 is too high a gear for a 421 on gas unless you are running a bunch of timing or racing 500 feet. You dont need to be geared to run 100mph I'd bet if you had 15/44 and start in 1st it'd be a lot better or about a 14/43 to launch in 2nd. My 421 on gas needed about a 14/43 to pull hard off the line in 2nd but would launch in 1st with a 15/43 15/44. A gas cub doesnt have as much tq off the line with 4 or 5 degrees of timing as we would like sometimes. I dont think you have a pos just a little tuning and it'll be fine. Quote
shanYE west Posted June 8, 2009 Report Posted June 8, 2009 If you tried a 45 pilot and no change.. Sounds like a air leak. I'd do a leak down and rule that out first. Jetting a motor with a air leak is like a dog chasing its tail. That surface with your rider weight should pull a 15/40 gearing. Quote
okbeast Posted June 8, 2009 Report Posted June 8, 2009 I would think that surface with just stock tires basically would pull damn near any gearing and not bog. Quote
RadarRacing Posted June 8, 2009 Report Posted June 8, 2009 I assumed he was running paddles my bad. Our local track is a tilled river bottom dirt track with sand mixed in and we run paddles. It's heavy stuff. Quote
wesw Posted June 9, 2009 Report Posted June 9, 2009 talked to him today he put a 58 pilot in and it seemed to help the motor run better and is goign to gear it down. didnt ever think a cub would like a pilot that big but it does. put a 52 in and could only open the air screws 1/2 turn it liked them to be closed. bigger pilot seems to be helping with throttle response. Quote
wacko2000 Posted June 9, 2009 Report Posted June 9, 2009 Would a properly setup 4mil pull lets say 16/41 better than a cub bc of more low end from the stock cylinder bike? I run 16/41 on my bike now and I have no problems launchin in 2nd, except for almost flipping backwards. Quote
sheefreak Posted June 9, 2009 Report Posted June 9, 2009 That just seems like a huge pilot.... I run 52's or 55's on alky in a 39 mm carb. Quote
wesw Posted June 9, 2009 Report Posted June 9, 2009 each bike is different but it like it so i think he is happy. its a cel needle and lot of people run that so again. Quote
bry Posted June 10, 2009 Author Report Posted June 10, 2009 each bike is different but it like it so i think he is happy. its a cel needle and lot of people run that so again. yeah a 58 pilot is what i needed now i have snappy throttle and it revs super high changing gears but had tornadoes today so no luck getting to run it. going to put a 42 rear and try it.. Thanks WES for the input you rock!! :beer: Quote
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