Backfiring during deceleration

I have a 2010 kx250f and when ever I open it up or just go through the gears the minute I let go of the gas she backfires alot.. why is it doing this? Any suggestions?

Stock exhaust?

Check for exhaust leaks?

Yeah it's stock and I will

Backfires, as in KAPOW!!!!!! Or a popping, "pop pop pa pop pop pop"? Two different things.

It's the popping like pop pa pop pop pop

I'll be sure to check my exhaust as soon as possible thanks!

Yeah I checked my exhaust and there wasn't any leaks. Could it be my jets or the fuel screw?

Leaky hot start do to carb neglect

Loose carb boots

Bad fuel screw oring

poorly adjusted fuel screw

Bad header crush washer

bad exhuast valve clearances

Yeah I'll make sure to check all of those.. thanks!

Edited by young_ridin

Lean fuel screw setting is easy to rule out. Just come out with it another 1/4 turn at a time between rides to gauge the different settings.

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