Coolness!! I was riding mine around quite a bit today. How fast does yours go? Mine only does 27 right now, but it's got a tiny, tiny, tinytinytiny exhaust on it. Mine starts four stroking when i go downhills and it hits 30. They use dellorto 12/12 carbs. I was thinking maybe a 14 or 15mm dellorto off of a minarelli might fit, though. I don't have any minarelli bikes sitting around to swap carbs with, though. You've got a couple minarelli bikes, don't you? You should see if it'll work.
Oh, also, when you lift up the seat (it tips forward when you hit a lever on the back of it), there's a vent for the back half of the gas tank. I think that's supposed to be open when you ride or is supposed to be opened and closed occasionally to get air in the back of the tank so it doesn't create a vaccuum and hold gas away from the fuel tank outlet. Just turn it so it's in the middle of being turned in all the way and out all the way.
One more thing. On the back of the left side of the swingarm, there's a button and a small lever. Push the button in to make it pedal like a bike. Flick the lever down to re-engage the drive system.