This is on a Hanger 9 SHowtime 50. The specs call for a. .82 four stroke. I am using a Saito .91. When I originally mounted the engine, I had to shave some of the insides of the engine mount to get the engine to fit. I wasnt really crazy of the idea thinking I was weakening the mount. In order to get the engine to fit, I need to space the mount holes on the firewall further apart.