yamaha aerox PM 70 kit

i have a yamaha aerox:
PM-70 kit
PM-70 crank
PM-Gear up kit
PM Pipe
PM- Clutch
Polini Variator with 4.25 gram rollers
Polini belt
17.5 Carb

But still it wont run 100% please help me!!!!!!!!!.......
it will pull away fine and rev up but then as soon as it gets to like 15-20mph it dies but once it gets to about 25 again it will pick up.Its really wierd and it really starting to annoy me has any1 got any cuggestion ???
Thankyou for looking

 

I would be thinking a tad lighter on the rollers, and from there be thinking about a carb flat spot, more dialling in required.

 

Thank you very much mate,, soo you thinking need to play around with the carb abit then?

 

only you know what you have done already with the carb, but most likely you need further tweaking, main jet and needle clip position.

 

Thankyou

 

i had some prob nd turned out just be a flat roller