Got a 49cc kit, still breaking it in at just under 250 miles now. Took a while getting mine started, later found I hadn't tightened the head bolts very well. Ran pretty rough the first few tanks. Seems to be getting stronger and smoother running all the time. I know not supposed to open it up this early, but I am impatient as heck! On a level road it got to 28 mph, next day, 29 mph! Oh, I did some porting of the intakes and exhaust before mounting it, the reason the bolts weren't tightened to spec! No reason to believe yours will not do better in time. best of luck!