I recently brought a near new second hand chinese 110cc quad for my kids. It had an electrical problem apparently and wasn't running when I brought it, and I paid $100 - I thought at that price it was worth it, as similar models on e-bay were selling between $800- $1000.
As I consider myself to be reasonably handy, I looked at it myself. It was frustrating because the wiring is crap and how they colour their wires is different (ie, red is not positive and black is not negative). After having a good look at it, and replacing a couple of electrical components, it still wouldn't run, so I started to ring around a few motorcycle repair places.
No-one would touch it. As soon as I mentioned it was a chinese quad they weren't interested. Don't know whether they were simply prejudice against this style of quad, but most said they could spend hours trying to fix it as these chinese bikes were all put together differently, and the problem was probably minor but it would take hours to find. Most places suggested for the price to have it fixed I might as well throw it in the bin and go buy a new one.... which wasn't a help to me!
Anyways, a friend of a friend was an automotive electrician and checked it out, and after a lot of hair pulling fixed it for $100.
We’ve used it a couple of times since then and it goes okay. It kinda looks like a name brand bike, but you can feel that the quality is not there. It feels fragile, suspension is ordinary and the thing vibrates badly at high revs / speed. The master cylinder for the rear brake started leaking and we lost the brakes, so I replaced the master cylinder. Brakes were good again, but then the next time we used it the brake line split. I’ve also noticed now the electric fan has stopped working.
The bike has probably cost me $400 all up, which is probably 1/10 the cost of a similar new, name brand bike. However, in all honesty I’ve spent more time fixing the thing damn thing than the kids have spent riding it.
We couldn’t afford a name brand bike for our kids at the time, but this whole process has been a learning lesson. I'd suggest if it's something you want to keep for a few years, spend the money on a proper name brand one. Right now the thing has been shoved in the corner of the shed until I get motivated to fix it ....the upside to this is that the kids seem contempt just sitting on it, making engine noises and pretending their riding it..... whatever it takes to get them away from the TV.