This morning I pulled the CVT cover, not easy, pulled some plastics removed the air box and pulled all the bolts. The belt was about 1/4 way up the variator and 1/2" down the clutch, that wouldn't do it. I pulled the drive face off and saw the belt was about 2 1/2 mm bigger at the bottom. It should be the same size so you have lots of power to get moving. I took dimensions and a washer that rides behind the ramp plate and off to Ace. There I found machine spacers, they were 1mm thick and the inside was just a little smaller that the shaft. I also found washers that were the size of the shaft but bigger than the boss. I got a bolt and nut to make a hillbilly lathe and headed home. The machine spacers were just a little smaller than the shaft but a perfect match to the drive boss. I took the dremel and slowly made the spacers a larger ID. One concern I had was whether the belt would have full travel on the variator with the shims so I put the faces together without spacers and put the belt in and it was higher than the smaller pully face. Which explains this groove in the case at the variator, there isn't much room for error here. When I put the variator together with the 2 shims it was perfectly at the top of the variator so that problem was solved. It also explained the belt thread I found in the clutch when I cleaned it. I think this was a design flaw with this variator on this model, when I looked at the parts diagram for this year the drive boss number was replaced with another number. On later years its all sold as one unit no separate boss. With the 2 shims in the belt inside was right at the edge. That looked good so I put it back together and started it and it was one noisy puppy. I pulled the CVT cover and found that the drive face hit the air deflector and scraped it. Off it came, next time I'm in there I'll sand the fins down on the drive face to get clearance. The belt was still not perfect so I tried a third spacer. Closed it up, started it again and reopened it and found the belt out past the clutch edge and way too close to the case. I didn't want to cut into the case because it was a little thin and the 2 shims got me everything I needed so I went back to 2 shims. I put it back together and took it for a ride. Problem solved, it pulls away just like it should and shifts up nicely.
Another possible way to solve this is getting thinner belt, I didn't research this but you then get into quality and other concerns. Maybe originally Piaggio had thinner belts but the wide ones are whats available 11 years later. I don't know if the Multivar or Polini variators have a larger drive boss but much larger you will hit the air deflector.
It may be a while before I open it up all the way to see how it does at wide open throttle but it definitely has nice low speed pull. This is all part of tuning a CVT, it isn't just rollers/sliders 10gr/12gr. or plug and play parts someone said would work. Its understanding how the transmission works and making yours work perfectly for your weight and driving habits. I'm just offering this to any one that has had this problem. Here are some pictures:
Belt in variator without the spacers
The belt before the spacers
The belt after spacers
The belt with the variator all the way closed, like you were running WOT at 85mph
What happens when the belt goes out farther than the variator edge. yes you'll go faster but at a cost of a belt breaking.
As you can see if your past the edge you have no place for the belt to go. Thats how they eat the gasket on the oil sump if its not trimmed.
This is why I stayed with 2 spacers.