A custom design for making a two speed transmission from available parts.

[lazylightning@mail.r]

I was studying the parts in the CD and CT 70 motorcycle engines and trans assembly (blueprints). The section where the gears are is very compact. I think it would be possible to take some of these parts and make a two speed gearbox that would bolt onto the place where the engine chain sprocket cover is. The small sprocket on the engine could be replaced with a gear that would mesh with the rest of the gears in a compact assembly that would allow one to shift up one time, maybe twice (three speed). This would probably be more than enough. If the proper gearing ratio is used then a two speed would deliver a really high top speed, especially if you already have a smaller sprocket on the back wheel. It would be in close tight to the engine and just to the side of it.
Any thoughts from you engineers and machinists out there? These old unrebuilt ct70 engines are in great abound and could be a good source of cheap parts.