Sorry couldn't control myself, came past this online and just had to order one. Just for dicking around. Less then 80GBP delivered to my door! Curious to see if it wil even run! Seems like they're a dime a dozain on ebay and the other usual china import suspects. They come in more expensive versions and rebrands also it seems, but it wouldn't surprise me if all those look-a-like engines came from the same factory. Anyway went for the cheapest one I could find, as this is not meant as a serious purchase ! I had never even heard of the concept of a "motorized bicycle", you don't see them were I live. Curieus to see if I can get this thing running on a old bike of mine, should be good fun anyhow!

http://www.benl.ebay.be/itm/231848324245?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

PS: if the link expires, just ebay search "80cc motorized bike kit".

 I see folks running around here all the time on them.  Look like fun. I'd give it a go