Gen II has a steel lined cylinder for durability. The flange mount carb is the same as the clamp mounted carb, but because of the mounting, the engine will fit in tighter areas without interference from the carb. (the canted spark plug helps too) These will fit in most 24" frames without much hassle at all. Overall, the included hardware kit and construction is a couple of notches above the rest of the "Happy Times" engines.