Few questions about slow Piaggio sfera / zip 1

[padly1995]

Hello,
I`m talking about sfera, but it`s the same scooter as zip 1 (only plastics are different).

It has dellorto phbg 19mm carb and free flow filter, it`s jetted to #75, spark plug is coloured nice brown.
I installed new belt and improved top speed from 47kmh to 56kmh (measured via gps).

I can tell that stock roller weights (5,2g) are too heavy, it has poor acceleration and it tops out at 54kmh.
4,5g ones are alot better but I can get same top speed and better acceleration with 3,5g ones.
Cylinder and piston were changed before about 500km.
The biggest problem is that it will not top out over 45kmh in slight wind :S


Can anyone tell me how sfera / zip 1 should go compared to yamaha aerox or chinese 4t 50cc scooter or old typhoon.
I never owned scooter that old so I don`t even know what I can expect from it.

Thank you for help