I rode a bike bug before i actually like it i thought it went pretty good for a 26cc engine. There getting 28mph outta their engines. Thats over a mph per cc. If the 40cc or 80cc were that efficient people would be getting hurt..I like those engines cause the design was so simple no clutch. it was easy as pie to install and i see my buddy riding his to work a few times week so i know they last. i gotta tanaka that i like ride that i built my self outta 15 year old engine with a hand balanced crank and the engine runs at 11,000rpms so it hauls butt..thats an understatement..lol..its probally the fasted kit out there. the 4 strokes run 5,000 rpms and some 2strokes run up to 7 but no other engine can touch this old school tanaka..it stinks they dont make these engines any more..i will take pics for ya guys..its impressive how the built these things.sounds like a airplane engine when it winds up!!!