I'll show you how to enlarge the intake for a 13 mm Dellorto SHA, adjust the transfer and boost ports and adjust the inlet timing on the crankshaft.
Degreewheel and software can be found on my homepage:
http://12v.dk/piaggio-moped-engine-tuning/
The video for rebuilding the engine can be found here:
https://www.youtube.com/watch?v=VzHsh8BVPwQ