I just ordered the chain version of the scooter motors and wheels. Because the generic belt wheel I got is wider than the original Razor part, and because the belt is too big to have both wheel and motor close enough for both to fit inside the foot shell, I have to admit defeat in trying to make it work. Oh well. Live and learn. I did some reading today at Astromech.net and other people have said not to bother trying to get the belt version to work without the original wheel.
So now I have two motors, two belts and two wheels I cannot use or return. Drat. Well I know there are other people who use the belt motors (they have the original wheel). Maybe I can at least sell the motors and belts.