[elhigh]

I know it's running on dead dinosaurs, but there's lots of bike engines, too. The upside of them is most deliver over 150mpg. Some are also terrifyingly fast: over 40mph with the right gearing.

Also try Googling "Dave's Insane-a-cycle", a homebuilt jobbie that breaks 50mph with an Etek motor. It destroys about two chains a year, if the writer is to be believed, and I think he is.