Maybe I missed it, but to really assess mileage, I'd need to know how much you weigh, how much the stuff you carry weighs, how long your average trip is and how fast you accelerate. There are lots of things that can change your mileage a few miles either way. On my 150 I get about 63 mpg, but if I use it on the freeway much that goes down a bit. If you ride around at 40-45 and rarely stop, you'll get great mileage. A worn belt will lower your mileage, worn rollers in the variator will too. If you weigh 250, your mileage will be lower by a lot compared to a 130 pound person.
Finally, I know it's an old story, but every time I find I can't change the idle much with the pilot screw it's because of a faulty bystarter. Make sure the gaskets on it are sound, so it's not leaking air around it. On one scooter I finally took the brass ferrule and needle and spring off a broken bystarter, dropped it into place, plugged up the large opening fully with gas resistant foam, capped it with a piece of plastic screwed down with the 2 screws that held the bystarter clip down and just eliminated the whole bystarter circuit altogether. The scooter runs great, the mileage went up a lot, and starting it, even after sitting for several months, is pretty easy. Probably would be bad at 30 degrees, but it's not 30 degrees here and if it was, I wouldn't ride for fear of ice.