NRG Power won't rev past 7000rpm?

My old streetrace 70 kit died, which i thought was the reason for the max rpm constantly changing between 7200rpm and 7800rpm, sometimes 9000rpm etc, ive fitted a new kit and carb, but it is still stuck on 7000rpm? when i first set off the revs will shoot up to 9-10 if i want it to but terminal velocity is always 7k. very annoying, can anyone offer me any advice as to what is causing this?
acceleration is also quite sluggish and spluttery when held at half throttle, doesnt become a crisp 'eeeeeeeeeee' until it reaches 7k but will go no further

4g rollers
stage 6 streetrace 70 kit
motorforce 21mm carb
standard airbox with performance sponge
72 jet
stage 6 pro replica exhaust

 

Tried heavier rollers?

 

well heavier rollers would make it rev less, so no i haven't

 

Why does it need to rev any more lol? Your pro rep doesn't make power over 8k..

You don't choose rollers based on how much you want it to rev you use the right ones for your transmission set up.

This is a transmission problem, and seeing as the only thin you said about it is that it has 4g rollers in I'd guess it's wayy off the mark