re-jet, or something else?

I have a 2003 yz450f that pops and sputters when you are at a constant throttle. It also backfires a lot when you let off. The float also sticks sometimes and dumps gas. What should I do, lean it out?

Or is it the nidle valve or something?

First, you have a needle valve issue. Either the needle is worn, there's dirt stuck in it, or the float is physically sticking. You should resolve this before diagnosing the part throttle problem. Once you are sure the float level is always what it's supposed to be, you can see if your sputtering problem still exists. If it does, it has the sound of being lean. Try first just backing the pilot screw out a 1/4 to 1/2 turn. Following that, you may want to raise the needle a notch and see how that goes.

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