05 TRX450R Backfires at high rev

[cyclelady]

have an o5 trx450r that backfires at high rpms. changed cdi,rev box, and stator all at different times to help find which one it was after stator change it worked great for about 1 hour then back to backfiring . Help !!!!!

[d3ktrix]

Timing chain stretched?
Check and see if the chain is taunt on both the front and back sides of the cam gear.
My friends 08 was doing this and his timing chain was so stretched that the tensor didn't even make contact with the chain.
Though I'm thinking his was ran w/o oil tho because it had other problems.

What is ur jetting?
Also check for intake/exhausts leaks if you haven't already.

[k265r]

could be a lean condition check your jetting

[longtimeridr777]

Yea check your jets, i had a yfz that was back firing at high rpm, i adjusted the jets and it ran great.