I love 2 strokes, and have a 150cc 2 stroke scooter and a 250cc 2 stroke dual sport bike. But the 2 stroke engines coming from China are very poor quality. I wish the Japanese would start making these engines. They would probably run forever. But since the only 2 stroke bicycle engines are from China, I am running a Honda GX35 4 stroke. It requires pedaling a couple of times to get started, but will reach speeds of 20 mph, which is the legal limit in my state, and certainly as fast as I would want to go on a pedal bicycle. We also have a 48cc limit on engine size, which was mostly based on the 48cc Chinese 2 stroke. I doubt any state allows an engine bigger than 49cc, so anything bigger is a moot point, for street use anyway.