One of the better kits I got was from Canada.
http://www.kingsmotorbikes.com
It could be that I just got lucky but, I really liked that kit. I am currently running one I got from GASBIKE but I had some problems with kit they sent me.
The CDI was defective and the chain could not handle the output of the motor. It shipped with a standard BMX chain.(maybe that's why it was on sale)
The one I would avoid at all cost is Boy Go Fast. That was the first kit I got and all of the parts that I installed failed. I guess it wasn't so bad because I did get to learn all about how these little engines worked and even with all of these problems I was still only out the price of a down payment on a used motorcycle.
mike
Why avoid b.g.f.?
he doesn't manufacture the engines or the kits..he just drop ships them like everyone else does.
chances are that b.g.f. gets the same exact engine kits that all the other vendors get.
sometimes you end up paying more for the same exact thing from a diffent vendor because they claim that thiers is the best (when in fact they are all the same exact thing).
the main thing to look for when it comes to different vendors is their customer service. Some people (like me) don't worry too much about customer service.
but, you could pay $150.00 for a kit from a place that has little to no customer service. On the other hand, you could pay $250.00 for the same exact kit from a vendor that has good customer service.
With these engines, it's the luck of the draw because every vendor sells lemons no matter who you buy from.
I have bought 4 engine kits from b.g.f. and have not had one single problem out of any of them.
I'm not saying that b.g.f. is the best because we all know that's far from the truth.
I'm just saying that whenever you buy a chinese 2 stroke, from ANY vendor, you take the chance of getting a good one, or a bad one.
the key is the customer service, and a vendor who stands behind what they sell. If they sell you an engine kit with broken or missing parts, or an engine that won't run, they should replace those parts (or the whole kit) for free in my opinion.