There is some misunderstanding here: A CVT has to use a belt, never a Chain. Go to youtube and watch any of hundreds of videos showing CVT's in action.
The 'Final drive' on scooters/ motorcycles, can be by chain, gears, belt or ring and pinion.
My order of approval is: ring and pinion and belts on larger bikes and then chains. On scooters, it's gears, chains or belts.
Sam:)