Thanks for the welcome. OK if y'all are interested- Pick up the new bike next week. From what I have read, there is no way to tell a 50 cc from an 80 cc motor.Other than taking the head off and measureing the width of the bore?.They are saying the motor will be 80cc 2 stroke. I've read that these are actually only 67cc...Also the bike has disc brakes, and it appears only the 36 tooth sprocket will fit under the caliper.Could I go with back cntr pull in order to put a larger sprocket or not enough stopping power? Dang! Running out of room here and still so many questions. Thanks mangs. p.s. ... My new wheels will henceforth be called Greg. I decided.