Motor came out of my boat a long long time ago for first set of pistons and rings. Took it down and a friend said "I have a 650 you can have" so this motor was put in a box and stored in a climate controlled basement for probably over 20 years. No longer have the boats so all my extra parts are getting sold. 

Kerker pipe and carb are already sold. This motor is really a good find. Hone pistons and rings good to go. Bore is 75mm.