started running like s***

[lawmaster891]

well i got back from spring break and went to take my 400ex for a ride and it was running very bad. it started sputtering and backfiring. i dont get what it could be it ran fine when i rode it a week ago. i tried to readjust the fuel ratio screw and no luck. my jets are 148 and 38 with the screw 3 turns out. i have a k&n with lid on and a slip on pipe. it has always ran like a champ with these jets. i also had cleaned the carb about 3 weeks ago.

[quad2xtreme]

any time something like this happened to me, it was new dirt getting into the carb.

[aDviSol2y]

if you have the pre-filter on the k&n, take it off and see if it still has the same problem.

[lawmaster891]

thanx for the help guys but the intake boot was slid out a little so after i pushed it in it ran like a champ

[jcs003]

Originally posted by lawmaster891
thanx for the help guys but the intake boot was slid out a little so after i pushed it in it ran like a champ

its always good practice(on any bike0 to check all intake connections. an air leak will destroy your motor.