Yamaha 6 Millimeter Multi-Port Stroker, this motor is freshly rebuilt with 82mm pistons and rings. It has a brand new RAD Crank. The cylinder and cases were ported by Ed Brazina for Riva Factory Racing. The Head is a redomable Riva billet head. The engine has 195 compression and runs on race gas. This motor is ready to go. Fresh rebuild and water tested only 1/2 Gallon of gas. This was built for my 2007 World Finals Ski and back flips great with ultra-light hull off of a small wave. Run this motor this season and have your favorite shop turn this motor into a 6mm BIG BORE!