1997 Kx250 Rev'ing high

[aagrena]

So...I recently purchased a 1997 kx250 as a project bike and have gotten most everything in working condition. The only issue im having that i can't figure out is with the reving. I started the bike up, it idled great and then the second you give it just a little bit of throttle it will rev up uncontrollably -- even when you bring the thottle grip all the way closed. Any ideas of what is causing this and how I can fix it???

Thanks in advance

"Nothing scarier than a 250 two-stroke reving uncontrollably on black top" :yikes:

 

[TWRT]

1. frayed throttle cable?
2. carb running out of gas? something not letting enough gas enter?
3. air leaks?
4. reeds?
5. something sticking with the slide?

Dave

 

[2strokerfun]

If carb is functioning properly, it is usually an air leak. Often at the carb manifold or left side seal behind the flywheel. I've had them run away so even the kill switch won't stop it. Had to kick 'em into gear and pop the clutch to kill the engine.