Thanks for the suggestions.
I built a combustion chamber pipe and installed the new carb... what a difference. It revs nicely and the clutch does engage- you can watch the primary contract and the secondary expand. The deal w/ the belt is that it is a bit more narrow than the EzGo belt- its not too tight, it just does not fit quite right.
Now, I need to tune the carb. It won't stay running at idle, in fact, it really has to be "goosed" (high rpms) to keep her going. There are two adjustment screws on the carb (a Tillotson HR7A) one marked H and the other L. Any suggestions?
BTW-
The Robbins is ok for a motor, but because it red lines under 4k, you just don't get too much faster than 20mph. Also, I sold the Robbins for more than I have in this whole project. Besides, this is fun! I might pull this motor and install a 500cc this winter if everything works out ok.