Well, I've bought well over 25 kits from rose326/mingsinternational/zminglu and have had very few issues.(Two bad coils replaced free)
While buying from ebay is always a bit of a risk, this vendor has been great to me.
Decent kits at a decent price. Why pay more for the EXACT SAME KITS from bikeberry/gasbike/etc?
I'll stick with the best price.
Two of my three engines are from eBay, both are fairly good. One is almost 3 years old with no problems. As long as you prep the engine before installing it you should be OK. A lot of new builders are worried about warranty, but I like a lot of members here on the forum pull a new engine apart and make sure everything is cleaned out from the factory. I do a little porting before it ever goes on a bike.
Two of my three engines are from eBay, both are fairly good. One is almost 3 years old with no problems. As long as you prep the engine before installing it you should be OK. A lot of new builders are worried about warranty, but I like a lot of members here on the forum pull a new engine apart and make sure everything is cleaned out from the factory. I do a little porting before it ever goes on a bike.
My oldest and highest mileage engine was bought on ebay from boygoesfast back in the fall of 2009 and its still running great, not a real high mileage engine but ithas well over 2000 miles on it now.
Its a lot to do with setting it up right, using a quality oil and the right mix and dont try to blow it up or you will....
2 Ebay motors kits have been fairly good, 2 have been rubbish.
1 was really crap.
I think it's worth spending a little more myself.
But If you strip the motor and go over it , wash the case out, ect,
You get what you pay for.