Ponder no more. You should leave it stock stroke/port. If you don't wanna over heat.. My stock cyl 4mil overheats in the dead of winter when it's 10segrees out, and that just off idle... Goin to a 4 mill ruined my bike and took the joy out of life. I'm now a miserable person who lives in my moms basement and has no contact with the outside world, other then the Internet... And girls. Well let's say palma-la and her 5 friends are all I had in years