C50 Kid Kart engine - revving out of control no throttle

[Greg Bray]

I have a C50 engine that is revving like crazy without any throttle...of course I've gone through the carb and cleaned out all the jets, and tested for leaks on the seals, and am not finding anything.

Engine has been fine up until our last track day, where it just went haywire when he was out on the track (flipped the chain off and revved insanely).

Oddly, even the kill switch wont shut it off - I have to pull off the plug.

Any other ideas about what to look for here....my little guy is rightly terrified of the engine right now.

[Jim McMahon]

I know you said you tested the seals for leaks but how did you test them. Pressure and vacuum? Sounds like a like. If its still running after you pull the ignition then you are detonating either due to the air leak or some crazy ignition advance.

Check piston for detonation damage
Re-check carb and motor for leaks (incl vacuum).
Remember gasket between carb and motor has to be good too.
Verify ignition advance and verify the kill circuit is actually still grounded killing the spark.
Throttle plate is absolutely, positively closed?
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[Aaron Abed]

I had the same thing happen before...check the throttle sheathing were it goes into the sheath adjuster (usually along the waist of the chassis). Sometime the cable sheath backs out of the sheath adjuster and causes the throttle cable be pulled which holds the throttle wide open.

Give me a call if needed or snap a few photos of your setup and I'll see if I can help locate the issus.[/img]
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