Need help tuning my 17.5mm carb

[Zip_Racer_7]

I have an unmodified runner sp 50 which came with a 17.5mm carb. When i got the bike it had a 53 main jet in it, 6.4 gram rollers, and the air mix screw was 1/2 a turn out. Since i have lightened up the rollers to 5.7g, changed the main jet to 75 and the air mix screw is at 2 1/2 turns out, and the clip is at the top of the pin (leanest). The low end and mid range is very clean, but the top end is much to be desired at full throttle the bike is slower than the original settings. Does anyone have any ideas on this??

 

[Carbon_Fox]

The lower the weight of the rollers , speed goes down , accceleratyion goes up
The heavier the weight of the rollers , speed goes up , acceleration goes down

second , you shouldn't twist your air mix screw too much , just leave it std. and see what kind of color your sparkplug has and go from there

 

[Zip_Racer_7]

mmmm when i mean its slower i understand the roller weight made a difference. I meant that the rpms actually fall off as you get to full throttle. With the standard setting they never got that high be begin with, now they get higher due to the lower rollers weight but then fall off at full but i think the carb is the cause of the problem i think tomorrow i will take some time and mess with the air mix screw.