I recently installed an RK400 clutch on my Rotax 582. The pros are starting with no prop load and reducing the idle RPM down to around 900. The con is that when you land and shut the engine down, the prop continues to windmill. I fixed that with an electric solenoid lined up with the vent hole in the gear box. A piece of leather is pressed against the clutch rim when energized stopping the prop rotation. If you want more info contact me at  kentgnh@hotmail.com

Every thing you need to know about the clutch. Contact me at kentgnh39@hotmail.com