99 Yamaha SX revving out of control - Snowmobile Forum: Your #1 Snowmobile Forum

leerocker · 10-29-2009, 06:59 PM

Hi all,
Just picked up a 99 vmax sx 600. It was running crappy and wouldnt stay running unless it was choked so i cleaned out the jets. Now when I unchoke it it starts to rev out of control slowly. It will start at about 1800 which seems like a normal idle, but every 5 seconds or so it'll increase another 100rpm and before you know it the clutch wants to engage because we're between 4-5K rpm.

Anyone know what's going on?

Thanks for any help!!!
Lee from NH

DoubleClutch · 10-29-2009, 07:03 PM

Check the intake boots for air leaks and did you set the floats right.

leerocker · 10-29-2009, 07:39 PM

I didnt really mess with the floats. None appeared stuck or anything.

**RJ Gleason** · 10-30-2009, 10:11 AM

You have an air leak.
Check the mounting flanges.

leerocker · 10-31-2009, 09:26 AM

Would that be between the airbox and the carb or between the carb and the engine?

TheSnowPro · 10-31-2009, 09:12 PM

between the carb and the engine.