Well, after thinking about it on and off for a couple years, my dad and I saw a pretty slick looking two-stroke motorbike for sale at the prepper's convention in Prescott, AZ a couple months ago. Said I, "That's pretty neat, but if I were going to make one..." A little more than a month after that, I had finished this.
Schwinn seven speed beach cruiser with a 49cc 4-stroke from bicycle-engines.com and a Sick Bike Parts shift kit.
Seen in one of the pictures without the muffler, which got bent and installed later that day. She runs beautifully, but needs new brake pads (the stock ones on the bike were old and hard, and therefore crummy and very loud,) a new chain, and different gearing, methinks maybe the rear cassette from Sick Bike...