In the late 60's sometime some friends and myself figured how to get a horizontal motro from an old rototiller, 5hp I think, into an old minibike frame that had been sitting in a neighbor's back yard. Patched tubes and off we went. Did I mention no brakes?
We took turns riding that thing all summer and the next year I had saved enough mowing lawns and shoveling driveways to buy a Honda ct70h, the trail 70 with a clutch and four speeds (all straight down). Rode the tires off of that thing and, when I was 10 I wanted a Honda Elsinore. My uncle (who raised me) didn't mind the mini bikes but thought motorcycles were dangerous. When he caught me riding my friend's Suzuki something 250, he made a deal with me. Thinking I'd never be able to do it, he told me that if I raised half the money for a motorcycle he'd pay the other half.
The next year we went to my other uncle's motorcycle shop for an Elsinore but got talked into a Rickman 125 enduro, which was a MUCH cooler bike!
Rode the shit out of that, got my license, got a Honda 350/4, then a sucession of Harleys, then more Hondas, etc. etc.