Just to add to this thread if anyone is interested. My bike used to rev high and it was related to the carb (I think it is a common problem). Obviously check the obvious thing like throttle cable and idle screw setting but if you have ruled them out then it is likely a gummed up carb and or pilot mixture screw setting. I cleaned mine with carb cleaner and air line and turned mixture screw counter clockwise slightly and it fixed it. I cannot say which contributed more to the solution but it is definitely the right area to focus on.