i run a 12 tooth clutch and a 60 rear sprocket on a doodlebug and i cash out right at the end of the 660. i do weigh a lot less and the bike is fully built with a bully 2 disk but it seems like a lot of people run real close to my gearing or a 13 on the clutch with the 60 on the rear. there are so many factors that play into it though. David is right you have to get a tach and just test. its the only way to know.