bryan vivacity

I've got a vivacity 3 50 cc I've upgraded everything but it is still struggling to hit over 30 I've got an Leo Vince exhaust on it what size jet should I run and what's the air screw adjustment cheers

 

4 stroke right?
Unplug the restrictor wire.
35mph plus...

 

Its a 2 stroke it's got a 60 main jet was going to put a 70 jet just wondering what the air screw mixture was meant to be cheers

 

Do you know if there's anymore restrictions

 

Vario has a ring behind it.
The mixture is a special screw, looks like a circle with a flat edge