i just got done shimming the valves on my 2007 yz 450 and when i revved up the motor i noticed that it was popping a lot (but not at idle). i was wondering if this is a timing issue or since it has gotten much colder out, is it a jetting issue? any help would be appreciated.

Sounds like it's jetting. Have you tried to turn the air screw?

Thanks for the response, I have not tried that yet, but I was just worried I had messed up the timing up or something lol. I will try that tomorrow tough.

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