Not running too great... needs help

i disagree with Nougat (and everyone else) that says "they should break into a four stroke when unloaded, decelerating, or at the top of the RPMs."

i've heard this said a few times, but my bikes don't 4stroke at all. not under any circumstances. and if they do, i figure out the reason.

i know this doesn't really help your problem, Zack, i'm just sayin...

with a stock kit, 30mph (+/-) is about all you're gonna get. with the stock kit sprocket, it's just not gonna go any faster, no matter what you do. i've built a few bikes with the stock sprocket and they run great, but they wind out quick.

I've got a GT2B and a GT5. The 48cc never 4 strokes and the 66cc very rarely ever 2 strokes. They aren't broken in yet but I've never gotten over 22mph out of either one of them.

Zack

My bike has been in various stages of power and all itself. I'm about 205# and live where it is quite hilly. I've ridden my bike to work a few times and there are some steep hills. My 66cc bike will pull me up the steepest at 15-17 mph and I'm pretty happy with that. On the flats going WFO I had it up to 29 a few times then it kind of settled in at 25-27 which kinda bummed me out as I was expecting it to zing up to 35 or so myself.

I don't know if I'd worry to much about getting up to that speed without getting a shift kit or doing some work on the engine or getting a different sprocket, etc.

I unfortunately haven't ridden mine in a long time as I can't get it running. After 250 miles (+/-) I can't get the dang thing started. I've tried about everything the folks here have turned me on to but still no start. I'll play with it some other time.....

i don't own a china girl but shouldn't it have hi and low adjustment screws on the carburetor?

If it's an NT carburetor, all they have is an idle speed screw and an adjustable jet needle.
The main jet is replaceable too, as previously mentioned.