Super Jet 650 piston sizes??????

[KK 9]

Alright guys long story short I orders the standard bore size piston set and not it! The old pistons say 0.50mm and 635PS below it. I know now that is bored over. Is it bored .50mm over because it was a HUGE difference. Its a 90 superjet 6m6 motor (case). Need help want to be back on the water got this superjet on a trade has all the good stuff on it. What pistons do I need to order. All help is greatly appreciated.

 

[ProSouth]

you'd have to measure it. your engine could have already been bored to a 701. what do the cylinders have stamped on them?

 

[TheBuzzard]

50 means .5mm over stock size. if you arent boring it, then thats the size you need. 77mm is standard 650 yamaha

 

[KK 9]

I'm thinking its a 701 piston .5 over. I'm just going to mic it out take my ring clearance and subtract and go from there. She was an old race ski.

 

[Poizen]

701cc bore for piston is 81mm