Idle issues, Bike won't stop

[SFbike]

I was riding my bike the other day all of a sudden as I let go of the throttle it kept going. I killed the motor and started it back up and it immediately took off. I checked that there was no tension on the throttle but as long as the motor is on the rpm's are really high. It goes at about 60% speed when I'm doing nothing and there is no throttle tension. And when I pull back the throttle the rpm's are higher but it sounds really muffled and sounds like there is metal scraping together inside the engine. Anyone know what might be the problem/what I can do to fix it? Much appreciated.

 

[CrazyDan]

You might have an air leak after the carb. That would cause a lean air/fuel mix and make the engine pre-detonate (ping). It sounds like a ringing noise, the engine is combusting before top dead center and tries to reverse rotation. That puts stress on just about everything and makes the metal ping, or ring. If you ride with it doing this, stuff can break and flop around in the engine.

 

[darwin]

What motor and carb do you have?

 

[Tyler6357]

Are you certain the carb slide is going back down when you release the throttle?

 

[SFbike]

Thanks for getting back to me so quick. The motor is the Huashengtaishan 4 stroke. Not sure about the carb. As for the carb slide, I am fairly certain that it is going back down. @CrazyDan would you know how to fix the problem if what your explaining is the case?

 

[CrazyDan]

You can check for an air leak by spraying (from a spray bottle) some water at all connection points between where the carb attaches and the intake port. You are looking for any spot that can suck a tiny (don't dump water on it) amount of water, it'll make the engine hesitate momentarily. If it does, tighten your connections or replace gaskets.
I'm not using a slide carb, but I've heard of folks re-assembling them improperly can cause them to have a really high idle. Maybe someone on here can chime in on slide carbs if the spray test shows nothing.