Originally posted by dwsc
I think that the rpms are good but i think the can be better, what are you drilling out?
I drilled out the exhaust exit hole in the back of the muffler. The 500 rpm increase came from a combination of the enlarged hole and the baffle being removed. This did not seem to effect back pressure for the fuel tank. O.S. replaced this engine with a brand new one after the liner peeled and I do not have any rpm figures on the new one yet.