Aerox 100cc old problem

Hi all shackers. I no longer own the bike and havent for a good couple years but the problem still bugging me so want to know for future referance/fix.

The problem...
It was a Yamaha aerox 100cc AC but had a 120 kit on it that was blown so i replaced it with a standard 100cc kit and sparkie. It had a sports exhaust, and stock variator/clutch. It fired up first time and idled perfectly. When i went to ride it tho it used to only go about 2mph and that was it. Used to run perfect beforw the 120 blew but I never new what it was and still bugging me incase it was a easy fix.
Thanks in advanve. DAMIEN

 

Dont worry. Of what i have read on the forums and figured out i guess it was a simple play with the rollers.
Wish i never sold it now as i bought it for £200 spent about 150-200 on it and sold it for £200