I got up to 50 a couple of times. 80cc schwinn beach cruiser ngk plug/plugwire, 1 gear all stock. You have to push it passed the point it sounds like its going to explode and have a wide straightaway, mine has a 55 mph speed limit, so if u dont go fast you`ll get run over. Its hit and miss 30% the time it breaks down afterwards all vibration issues. Ive been told its leaky and air is getting in and im running rich. but it hasnt blown up yet.