Where are you buying your motors? I have a friend one with he mounted but it's very old and uses a basic setup with a spoke with teeth that grip the wheel. Pretty inefficient.
I would rather get a really small motor that is 4 stroke, is this possible? 2 strokes seem to smoke and stink alot and if you have that on your bike in an inconvenient place your probably going to get smogged out
Don't try to weld the sprocket onto the shaft -- sprockets wear out and must be replaced, and the welding heat to the shaft may melt the shaft seal.You would have to get a little sprocket thing and weld it to the end of the motor shaft....... how much is a welding machine I can do that with?
There are several methods in use.Whats a good way to attach it then? Would a belt system with a torque converter work?