As Toystory said, assuming that we are not talking about a CVT, chain drive would probably be superior for most go karts and minibikes. If you are thinking of a CVT versus a centrifugal clutch, you will want the CVT unless you are doing a racing kart. Once again, chain drive would be the better option for most karts and mini bikes to then link the CVT driven to the axle. Aside from a CVT, good applications for belt drives include: a v-belt drive tensioner clutch for those who do not wish to buy a centrifugal clutch, or a tooth/cogged belt drive for those wanting a quieter, cleaner, and maybe even smoother drive-train what compared to a roller chain. I would only suggest a non CVT belt drive system for on-road, or light duty off-road vehicles. A toothed belt drive could work great on a mini chopper, just be careful that you can get a toothed pulley for your CVT jack-shaft, or a centrifugal clutch with a toothed pulley.
