>>Does Honda/Vespa/Moby make speed kits for theirs? Could ya whip out the calculator and possibly find a cylinder/head/piston combination to fit one of the peds that came from one of their cycles? Measure the bolt pattern/stroke/etc. Seems like a real headache.<<
Vespa does...or did, as I recall - do not know where to get them, however.
Some of the Vespa parts will also fit Kinetics.
You could, with enough hard work and skull session figure such a thing, but it would wind up costing more time, money and effort than it's worth in the long run.
I do not know too much about the Moby, but with a Honda there's a few tricks you can possibly try...like mounting a CT-70 engine to one...I've seen that (it's a hell of a ride, but a real deathtrap with OEM brakes)...or perhaps a smaller 50cc.
As for straight moped parts, I would have to know exact models to make deeper suggestions.