'04 YZ450 not dropping back to idle


picked up a clean and well looked after 04 450 last week and ive had it out a few times now and its great,

the only issue so far is that it doesnt always drop back to idle after having the throttle opened, it doesnt make a difference whether im revving in neutral or riding in gear, i would estimate its around 500rpms above base idle

it doesnt always do it and the length of time that it does it for varies, i would say a maximum of 3-4 seconds,

ive popped the cable housing on the side of the carb off and everything seems in order, i thought it was a cable not returning or out of adjustment, but my search proved fruitless,

any ideas?



Try adjusting the idle mixture a bit richer (back the screw out in 1/4 turn increments. )

If that does no good, check the valve clearance.

Clean the carb. There is some sludge in there, is my guess. Probably not the cable.

If the carb has some fine silt in it, probably ridden in very silty conditions previously without adequate filtration.

As mention above, Valves would be next.

A malfunctioning/improperly routed hotstart cable could also cause this. Mine kept revving up when I turned the bars to the right - couldn't figure out why - ended up being the hotstart cable. Re-routed it and no more issues.

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