Vespa 75 cc dellorto 16.10 speed problem

Schaltroller / Classic Motoscooters Vespa Smallframe
1

Hello,

does anybody know what size of jets there must be? 

Vespa splutters on speed 30 km/h and I think it is going too rich.

 

BR,

P

2

Sorry but this carburetor is way toooooo small.
A 77cc cylinders needs minimum an SHB 16/16 with a main jet size about 72-74...