This is an old thread but want to re-open it to get some added advice.

My 4.2 69cc Brisson on a 1/3 scale Laser spins a 22*10 Mejlik 7700 RPM on the ground. Feeling this was to high I mounted a 24*8 wood Grish. It is a wide blade that has it only spinning 6000 RPM. I'm concerned this is too much a load and can't figure why it dropped so much. Any one have any experience with a 24 *10 Mejlik on this engine and the RPM it produces?