I believe my carb is the limiting factor on my 80cc because it will rev up to 7000 rpms for a few seconds then just bog down. I haven't tried to move the clip down to richen the mixture, that may help.

It'll keep gaining horsepower up to a certain rpm, then start dropping off. If the carb can't keep up then power will really drop off.

My bike isn't together right now so my help is limited.