Kx 250 Question

[chuck m]

I have a 1995 kx 250, what would make it rev out of control?

[Throttle Jockey]

When you say it revs out of control do you mean when it starts it hits high RPM's while the throttle is in the stop position?

Somethings to check first:
1. make sure your throttle is seated in the full stop position. I've had throttle cables start to fray and not allow the slide to seat fully in the carb.

2. check your idle screw, has it been turned in? should be 1-1 1/2 turns out.
3. A vacuum leak can cause this as well, check the intake boot for cracks.
4. check your throttle cable for frays.

Did this just happen out of the blue? How has the bike been running previously, or has it been running, also has the bike been sitting for a while?

A little more information would help to narrow down the problem

2.

[chuck m]

The intake boot is fine. The throttle cable is fine. The bike sat for 2 years but I ran it last weekend and it ran fine. It started acting up while I was riding this past weekend. I started it yesterday and it just ran fulll throttle. Can it have something to do with the reeds?

[nd4speed]

clogged fuel line?
Float(s) stuck?

Either one of those cause the bowl to go dry and cause a lean condition (same as running out of gas).

Was the gas left in the carb while it sat for 2 years? Gas evaporates. Oil does not. The oil hardens and causes all kinds of carb problems.

Air leak?
Blown base gasket or crank seal flywheel side.

Friend pickup up a Polaris 500 that had sat out side. Fixed it up, put fresh gas, plug, air filter in it, ect. Never drained or cleaned the carb. Test drove it for a whole day with no issues. Took it up to his cabin. Next time it would not run. He takes it to a dealer. They clean the gunk and varnish out of the carb. Problem solved.