Here is my review of gasbike. I ordered a 4-stroke kit and replacement flyweight. The 4-stroke kit quality was above average, the shipping was fast (within a week), and the packaging was done well. One of the clutch springs broke like almost right away and I emailed for a replacement flyweight or at least the spring. I didn't get a reply. I am not sure maybe I screwed something up and the spring broke, but I think it was just a random material failure. I guess gasbike wouldn't know that and maybe assumed the customer screwed up. I ordered a replacement flyweight and ordered the wrong one initially. I was able to contact them over the phone and they said they would mail the right one, which they did. However, this time there was no shipping email, but it seemed at this time they had personnel issues.
Overall, I think they have very good prices and they don't overcharge for shipping like other vendors. For example, the flyweight shipping was $2 on gasbike and $10 at another site. A few people order from them only via eBay so there is a third party mediator in case of a dispute. They also have a 100% rating ratio on eBay. I guess this is the best way to go. I would do business with them again.