It was chrome plated, and it did not have the angled spark plug. The studs are 6mm, not 8mm. Yet, I was impressed with the quality for the money. I researched the engine, and found that it is manufactured at this place in China.
http://ntjlqy.en.alibaba.com/
I know that BMW motorcycles discontinued cylinder liners in 1981, "Cast sleeves were discarded in favor of Nikasil coating for the cylinders, and the intake and exhaust valves were enlarged to improve breathing." So to me, liners are a step backward. Liners are heavier and can be rebored. Who wants to?
It's cheaper and better to replace the cylinder on these small engines, about $25.00, than to have them re-bored and a new piston fitted at $50.00 an hour labor. I had a 1981 BMW R100RT that my wife and I toured about 60,000 miles. I never heard of anyone wearing out the chrome cylinders on a BMW motorcycle. I'm not saying that a small inexpensive bicycle engine is the same as a BMW, but the chrome bore is similar.
I don't see any advantage to the angled spark plug either, except to fit the engine into a tighter space.
I'm satisfied with the GasBike engines, I just received another one from FedEx today. The price is right. I don't know about GasBikes service and parts, and there is no warranty. But, I have the name of the manufacturer and can gets parts elsewhere if needed. Like I said, GasBike was prompt and sent the engines immediately. Both engines were test run at the factory, and the one I opened up looked good. I'm going to tear down the the one I got today and check the base gasket in it.