How are does ebay engine kits ??

You tke your chances on ebay to save a few bucks. The rock bottom price mean you're on your own if something major is wrong. I've had good luck with BGF and also got a couple losers. In the end, not such a great savings. Now I will go with one of our vendors here who cares about reputation. Two I have experience with and can recommend are Pirate Cycles and Dax. With either of these guys if you get a bum engine they'll make it right.
SB

I ordered a ZB kit off ebay and was very impressed with their customer service and the quality of the engine (relatively speaking). I think gasbikeshop is just another face on the same company, can't confirm that though.