10hp from a 50c two-stroke is easy. Road racers were getting 17+ with 70's technology. Those engines also had about a 100 rpm powerband, though. So you'd see

10hp from a 50c two-stroke is easy. Road racers were getting 17+ with 70's technology. Those engines also had about a 100 rpm powerband, though. So you'd see 50cc bikes with as many as 14 gears.