RE: Max rpm range for an Enya .15?
It's mostly a matter of engine load that determines the correct needle setting. As the prop load increases, the range of acceptable needle valve setting shrinks. When running wide open, with a correct setting, the engine should speed up slightly when you give the fuel line a quick pinch. If it sags, then richen up and try again. What many don't realize is that the engine will need more fuel in the air as the engine unloads and the rpm increases. This also requires the fuel tank in the correct position relative to the needle valve, which sadly many airplane designers tend to screw up. The correct position is the center of the fuel tank should be no more than about 1/4" below the spray bar.