2004 yz 450f Jet?

i just bought a 2004 yz 450f the bike is completely stock except for a fmf powercore exhaust with a powebomb header. and a K & N air filter. i have never jetted a bike before and wondering if anyone has any suggestions for me? do i run stock jets with that set up or change it up? it backfires when decelerated too fast. any help would be greatly appreciated....thanks


If the only running issue is decel backfire, it is probably fine.

You have a race bike. No one who races coasts, so popping should not be a problem. You also have an open pipe which makes decel popping worse.

so i should be fine leaving the jetting the way it is for best results? yeah the only problem i am having is the decel popping.

Yup, status quo sounds good! Only fix something wrong.

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