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2002 yz250f: Bike won't rev past a 1/4 throttle need some help figuring out what the problem is.

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2002 Yz250f won't rev past a 1/4 throttle,  it bogs out.  I'm just trying to figure out what the problem is.

The bike has a fmf megabomb header stock slip-on, twin air air filter. 

It has a 45-pilot, 175-main jet, 72-jet screw is 2 turns out and the clip on the needle is 3 down from top. 

It starts first or second kick everytime. It does shoot flames out pipe, loud popping and the pipe gets hot not too long after start up.

Could it be timing? Valves? Jets?  

I'm just lost.

Edited by YamiLife

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Did it start doing this all at once? If so, I don't think it would be the jetting. If nothing changes, nothing changes. I had a similar issue with my 07 wr250f. Turned out to be the regulator rectifier. Since yours is a yz, wouldn't be your problem but could still be spark related.

Sent from my SM-G900T using ThumperTalk mobile app

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This is a total stab in the dark, but if you have cleaned and adjusted the carb and it is still doing it, I wonder if it is a CDI / ignition problem.  Or maybe your TPS is out of adjustment causing the ignition timing to go out of whack?  Just things to check.

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Ignition timing could go all weird from the TPS being wrong, I've never seen it but it seems plausible

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