The EZ Motorbike kit does use a v-belt for its primary reduction drive and then switches to chain for the final drive to the rear wheel. The output from the primary reduction can be changed from a sprocket to a pulley and then a Whizzer sheave can be mounted to the rear wheel to give you a totally v-belt driven drive train, but I believe that you need to source the small pulley and sheave yourself. But being as Quenton is into Whizzer in a big way he probably has everything you need. This change will probably add $150.00+- to the price of the already $650.00 kit though. I bet it would be a great set-up if the costs are not a problem for you.
ocscully