No idea, my RPM meter is in Canada and I am presently in Florida. I know I am near maximum speed, the engine is screaming high pitch. More over I measured the maximum trust with a scale and I read 9 1/2 pounds, which to me, seems very close to the top. This is my first gas engine, but I have a lot of experience with glow engines, turning faster than gas. I believe that if I approach max speed at 25% air flow, it is because the mixture is lean, also I will try to open the high speed needle valve.