Not sure of the year but my Super 9 that I bought new a year ago seems to slip a little and a getting a vibration may be from the belt. A Kymco dealer on the phone thinks that the mfg. puts too much grease on the pulley. Have not yet checked it with the original dealer. It has just about 5,000 km on it. Need an opinion.

Hi,
Looks like your torque pulley, located at the rear that drives the axle/wheel has the problem.
The friction material or clutch is already worn out and started to slide. Any motor bike tech can replace it with similar part or better buy an aftermarket racing clutch w/ spring that is much better and stronger than the stock parts.
Hope that helps you out.
Thanks for asking FixYa!

I bought my 2005 Kymco Grand Vista / Grand **** 250cc scooter 2 years ago with 2600 miles on it. At about 8K miles the scooter developed a high speed vibration. I concluded that the problem is the belt is worn. Belts wear unevenly the same way drive chains wear on motorcycles. That is to say the the belt is tight in one spot and as you rotate the wheel gets loose and the wheel is easier to move. It is mainly noticeable at high speeds above 60 mph. It is a constant rhythmic vibration. You can feel it by putting the scooter on the center stand and rotating the rear wheel - hard to turn , easy to turn then hard then easy. I now have 10K and am getting ready to replace the belt. It cost $83 at the dealer. I'm not sure why you scooter would have this problem at such low miles - unless it got really hot due to slow driving where the scooter is barely moving on a hill and not fully engaged so the belt is slipping and so is the clutch. That could shorten the belt life combined with age.