Well, from my experience, the main thing the Chinese need to improve on is electrics, pretty cheesy. The fit and finish is sub standard, but the little engines just run and run. I worry a little about quality of metal mainly just because the detractors site that as a downfall, but I haven't seen it yet.
I have two bikes now I've ridden a lot, a Jincheng 150 I got from Midwest and the Diamo LS200. I'll probably sell the Jincheng cause I don't ride it much, but it sure is a hoot to ride off road, a little TTR clone with a 150cc engine that's really well built. It is an impressive bike, but was more expensive than some of the other bikes around, the Diamo in particular and the little Kasumas. I've jumped this thing, really rung it out off road and it just takes it in stride.
A friend of mine runs Metric Motorcycles in Houston and he races minis with us in Texas Mini GP (
http://www.tmgps.8k.com ). He bought a 700 dollar 110cc electric start auto clutch bike running in the lightweight class and they won the lightweight novice endurance class with it last year. That thing was fast and reliable! I'm stuck with a couple of little XR70 clones here left over from when I was selling them. Guess I'll have to take a loss to sell 'em, but was thinking of turning one into a mini racer.
The parts interchange with XR70 stuff. They have the lifan 90cc motor, though. I could take it out to 110cc, put street tires on it. Then, I'd have to spring the suspension and figure something out for a shock. There are lots of racing parts for XR70s though and that shouldn't be a problem.
Anyway, I was impressed with Andy's little chino bike. A season of endurance racing is one heck of a proving ground for a motorcycle. They had only one problem that I remember, a clutch problem in the last race. Avoiding DNFs is half the battle in an endurance racing championship.
In case you're wondering what sort of racing I'm talking about, it's road racing little motorcycles. Here's a picture of me on my KX (157) chasing down Joe Prussiano on his takegawa stroker 150cc XR100 in an expert unlimited sprint race.
