Re: 2 or 4-stroke
I like the cg engines. They slip into the frame, are narrow, light weight, easy to fix and cheap.
To me the 4 strokes look like a lump, cost more, are heavier (counting their mounting plates), need wider cranks (don't they?) and use centrifugal clutches which I grew to hate as a kid on mini bikes.
The 4 strokes also require a little more knowledge to work on, with their valve clearance adjustments and whatnot.
The 2 strokes need mixed fuel and some people have problems with vibration loosening mounts and stuff. Mine hasn't had any problems so far.
Runs great and gets better every ride. I did put a different ignition and carb, but that was a choice, not something it needed.