why does fuel fill up the crancase in my chinese 150 atv?

My guess would be that the carby is flooding whilst the engine is not in use. The carby float valve is letting fuel through. It is possibly stuck or blocked open with some dirt; the float could have a leak in it and has filled with some fuel making it sink.

Pull off the carby bowl (bottom of the carby) carefully and gently blow into the fuel inlet whilst manipulating the float to see if the valve is working correctly.

The float is usually set in such a way the the valve is closed when the top of the float is parralel to the carby body/bowl interface.

Good luck.

Aussie Ron

Ron
January 2007