thanks for your reply and i am really appriciate this website.i have one more asking again. when i run slow to a bad road/way or just like a hump, my RPM arise, if arise my RPM, it will ran fast for 5 seconds and back to normal. but when i run very fast, my RPM is very good. my mechanic replaced new cable accelarator and overhauled my carborator to spray in 2 bottles of carborator sprayer. but still the same problem with my RPM.

thanks again..