Air-Tech Clutch (Rotax)

No one will ever dispute the fact that a 2 cycle engine is not happy at very low RPM's with a large flywheel attached to its PTO end. The flywheel of course is the propeller.

This dissatisfaction is usually responded to with severe shaking and rough running. This action can be easily proven by simply removing your propeller from your gearbox and then start your engine. You will notice that it hums like a sewing machine (kinda), well at least it's no longer trying to shake it's self off of the motor mount. The reason for this smoothness is due to the fact that the engine is not laboring to spin your propeller at idle RPM. Even with the propeller installed, the engine eventually will smooth out at around 2800 RPM.