The motorcycle refueled and then released the throttle to keep idling, but the speed soared.

Check whether the throttle line and throttle handle are too tight or stuck and cannot be reset in time, check whether the carburetor throttle is stuck or stuck, whether the carburetor mixing ratio is improperly adjusted, whether the throttle needle is not at the correct height, whether the valve clearance is too small or the intake pipe leaks slightly, whether the throttle is used or set improperly, etc. All these will lead to slow or untimely speed drop after turning off the throttle.