backfiring....

[dpizz450]

I have a 2003 KFX400, fmf head pipe. hmf slip on, uni air filter, and rejetted. Whenever i am pinned in 5th gear and i have the throttle maxed out it will backfire pretty damn bad. but if i let go just a little and only pressing 3/4 of the throttle it is just fine. its only when im all the way pinned in 5th gear. it does not backfire any other time. it's almost like its hitting the rev limiter or something? anyone know what this could be? could the jetting still be off a little?

[bossman525]

try lowering your main jet a size

[dpizz450]

anyone else have any input? please? :o

[JOEX]

Originally posted by YZrida
anyone else have any input? please? :o
My input...

You're either too rich on the main like bossman525 suggested or you're hitting the rev limiter like you suggested.

But...... this may depend on what your interpretation of backfiring is...

[CSR400EX]

when our buddy's predator 500 hits rev limiter in 5th gear, it pops and cracks and also shoots a flame out of the exhaust. kinda sounds like you are hitting rev limiter

[dpizz450]

Originally posted by JOEX
My input...

You're either too rich on the main like bossman525 suggested or you're hitting the rev limiter like you suggested.

But...... this may depend on what your interpretation of backfiring is...

yeah i think im hittin the rev limiter. cause i listened to it again and it was more of a sputtering and a popping then backfiring. is that what rev limiter sounds like? kinda sounds like the reverse rev limiter but i cant tell cause its at such a higher speed then when in reverse.