carb. jetting help

My wr450 2004 backfires and I need to know what to do to stop it. :thumbsup:

sounds lean, I would try richening your mixture a little.

SINCE i made mine run richer its has never backfired. I went up on the main and pilot. i think im running a 170 main and a 150 pilot( i dont remember????) but i also have a white brother exhaust and holes drilled in my air filter cover for more air and im below sea level. Runs great!!!

Richen the main jet by to a 168 or 170 depending on altitude and turn the mixture out to 2 1/2 to 3 turns. Get a JD needle kit. They better than stock. Also use a mixture of race gas (110+-) and premium (91+-) to get a 95-96 octane. Your problems should go away. :thumbsup:

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