While we're on the topic of motorized bicycles, check out this one that I built out of my nephews old broken down Schwinn Stingray Chopper... [8D]

http://www.youtube.com/watch?v=5NSTYA_wR8A

It's got a 1973 90cc Honda engine from an ST90. The old ST90 was given to my dad about 25 years ago, and didn't run at the time. He never did anything with it, and last year I pulled it out of the weeds and pulled the engine off. I tore it down and rebuilt it, and put it on the bike. Runs pretty good for a 35 year old engine! lol I ended up swapping the bike for some motorcycle parts though, and missed it ever since. Now I've got another frame out in the back, and another engine sitting on the shelf in the shed, I'm thinking winter project... If I do build another, it'll be a trike, I've got an axle on an old ATC110 frame that'll be perfect!