Installed my ys 140 dz today on taylor craft H-9 runs great didnt even have to adjust mixture just 2 turns out on high end i cant believe the way it idles really low cant hardly get the motor to shut off using Heli Sig fuel 22% nitro with 24% oil sythetic .Turning a apc 18/6 wide blade prop dont know what the rpm s are will tac it tomorrow Bruc e

I'll be real interested in the rpm readings on that setup. What muffler are you using?

Using the straight chrome header about 3 inches long no muffler sounds awesome will tac it today and let you know Bruce