Motorcycle Repair: High Idle, screw out, 3000rpm

Question
Hi Mark,

I have a 1982 Yamaha Maxim 750. It starts fine, and initially idles around 1500 rpm. As the engine warms up, the idle gradually climbs to about 3000rpm. As soon as I engage a gear it drops back down to where it should be, but any time I pull in the clutch or go into neutral it revs up again.

What do you think the problem is?

Thanks a lot!
Michael Nelson
[email protected]

Answer
Hi Michael,

The cause could be any one or any combination of the following:

Engine idle screw out of adjustment.
Intake air leak.
Throttle or choke cable binding.
Throttle or choke cable improperly routed.
Carburetors out of synchronization.

Respectfully,
Mark Shively