Help! Where should I start?

My '05 CRF450X has an aftermarket Procircuit TI header and silencer. When the bike is warmed up if I crank the throttle fast the engine will cut out, turning the throttle slowly will let the bike accelerate normally, and also when engine braking it backfires like crazy. Where should I start? Would you recommend changing to a different jet other than the stock? Thanks for any help you guys can give.

its 100% stock jetting?

yes sir, the only thing I've touched on the carb is the idle needle

start with confirming your pilot circuit by using the sticky at the top of the forum.

Thanks man- adjusting the pilot screw about 1 turn out makes it run like a top. No hesitation, no more backfire.


good to hear.

this is a good post about how a simple fuel screw adjustment makes all the difference.

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