Ok I'm a bit confused but here goes
Bike is a Shineray X1 with rounded CDI one bolt coil original regulator. Was original CG150cc

Engine - now here's the strange bit, I think 125cc CG but runs like shit

So if the stator is from the square CDI system this could be an issue? Timing and or other mixing of AC or DC system?
This I don't know if both systems are the same as far as the stators goes.
What's what square and round CDI plugs?
Is each stator and pick up and flywheels the same? Or are they different?

I need to be sure I have the correct stator flywheel and pick up sensor to suit the bike before I can look at other things.

Also now I upgraded to a PZ27 carb and new upgraded air box too.

I got the bike free with issues
I got it running etc and working thru what I know was wrong.
So are there variations to stators pick up and flywheel affecting timing and or ignition? If yes what type do I need for the X1? If no then I can eliminate this as an issue.

I think it's a 125 so my carb is too big and will run like crap, best change the barrel to 200cc tune carb and ignition should all match?

Your knowledge greatly appreciated