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View Full Version : no baffle no airbox what size jet?



exrider2502001
05-03-2003, 10:43 AM
what size jet should i run with no baffle and air box cover


peace josh

250EXking
05-03-2003, 10:46 AM
same.

exrider2502001
05-03-2003, 10:50 AM
i think it needs bigger but i dont know what size when i ride with out the baffle and air box cover it bogs right out and cnat get out of its own way



peace josh

OutlawEX
05-03-2003, 11:00 AM
I just need to Know WHY?Why would u run with no baffle nor airbox:confused:

exrider2502001
05-03-2003, 11:10 AM
its way to quite other wise i just ordered a white bros pipe

cals400ex
05-03-2003, 11:59 AM
i don't have a 250ex but i do have a 400ex with those mods and i can tell you what i did. sorry i don't know the jet sizes with the 250. i removed the lid and the baffle. the stock main jet is a 148 keihin. the jet i am running is a 152 keihin. so that is 4 sizes up. this setup works great. i am as fast as my friend with a pipe and a k and n filter. i would be beating him pretty good but i have aftermarket tires that are heavy and slowed me down. with this setup i also moved the clip down one position on the needle jet. this makes it a little richer. with an aftermarket pipe, i would read the instructions on what to jet too. i would then go up approximately 2 sizes on the main jet when completely removing the lid. for the people asking why do this? first off, they are removing the lid to get more air into the engine. more air will yield more power IF YOU REJET. without rejetting, you u will get NO power increase and will probally lose a little. the reason you rejet is because you are getting more air flow, a larger jet will give you more fuel. remember though, more fuel is not always better. a correct air fuel ratio is critical. here is a little info on the jets in the carb. the main jet effects 3/4 to full throttle. this is the most common jet to change. the needle jet is for 1/4 to 3/4 throttle. the pilot jet is for 0 to 1/4 throttle. many people replace this jet with a bigger one to make the bike start better in cold months. this jet will not help full throttle performance. while you guys are at it, make sure your throttle cable is adjusted correctly, otherwise your carburator will not be wide open when the throttle lever is all the way in. good luck and let me know if you have any other questions.

exrider2502001
05-03-2003, 12:18 PM
thanks alot




peace josh