that screw on the front really and truly isn't a true fuel adjustment but it does somewhat adjust the fuel by allowing the governor more travel on the fuel rack. in order to set the fuel you need to take the pump to a shop and let them adjust delivery. if you are concerned with the screw then remember if you adjust the screw out will alolow the gov more travel and in will give less. it won't affect RPM and that is important. if te Gov limit screw on the throttle lever has been tampered with then all you need is a tach and adjust it back to spec. is your machine smokeing??