I’ll just drop a pearl of wisdom for any belt primary drive vehicle owners, before Munch kicks us off this Cruiser thread 😮
Just like the Salsbury clutch on a snowmobile, 100% of the force is on the sides of a V drive belt, the rubberized nylon belt wears and friction burns rubber material away, until the hardened steel clutch cones are spinning against burnt rubber and expose nylon (or kevlar) thread material. This is why you should never roll on the throttle slowly with a CVT clutch, get on that throttle harder at first, so the clutch positively engages then back off on the gas to moderate your speed. Applying the throttle slowly before the clutch engages, equates to slipping a dry clutch on a standard transmission vehicle. Replacing the belt should make the grundle go away, and consequently, it will restore the original speed ratio that your bike had when it was new. On a seriously worn Salsbury clutch, the steel cone faces can have ‘chatter’ marks worn right into the metal and only replacement will cure that problem.
Did you know; Leonardo DaVinci sketched the first CVT in 1490 making your scooter’ clutch design more than 520 years old ! … maybe Leonardo worked with Piaggio 
