What gram rollers and/or contra spring i use?

I have an 2006 aerox. The engine is stock, besides a 17.5 carb, and a extra v2 exhaust. The transmission is Malossi MHR overange variator, malossi delta clutch, A malossi clutch bell, white clutch springs, 5g rollers now. It goes about 70km/h. What would i need to do to get it to do like 90 km/h?

Thank you.

 

And i have a red contra spring

 

From my understanding or what i read other say. Isnt overrange not beneficial on a 50cc

 

Yea its not your take off will never be like it should because the mhr overrange is designed for higher hp scooters, so it doesnt have that hole in the start, i would suggest you changing the exhaust firstly then rejetting, you are never gonna get more than 80kmh (realspeed) with that gianelli trash. Also 90 wont be really possible maybe with really good exhaust and perfect tune and 70kg rider.