Motorcycle Questions? Ask a Mechanic.
Have you ever changed the belt, or removed the variator to inspect the rollers? The variator uses weighted rollers that spin outward depending on the speed of the engine (balanced with the load on the transmission, ie your weight and speed) They will start to wear flat spots over time.
I upgraded my scooter (Honda Ruckus) to a Dr Pulley variator and slider weights instead of rollers, they have a much more consistent application and are available for the Kymco as well.
The squealing is likely your belt- as it wears, it rides lower and lower on the variator due to the width of the belt wearing down. After a while, and if you ride a lot at wide open throttle, the belt will start to slip as the engine speed wants to overrun the capability of the belt. This causes glazing of the belt and too smooth of a surface on the variator plate.
ok- you never said that the squealing was without the engine running. The belt is always there, always turning with the engine running- just not until your centrifugal clutch engages that the wheels turn.