Try roketa.com The 163 FML-2 engine is fairly common among the Chinese breeds, so you really need to find a place that has parts available. Terminator and Roketa were one in the same, and I think Yamoto, before they got sued by Yamaha and lost and disappeared, probably got their bikes from the same source. I think the source of manufacture for Roketa is Shineray.
http://www.shineray.com/
http://www.roketa.com/index.shtml
(Roketa is in the US, while shineray is in China, but it couldn't hurt to ask if Roketa can't answer you.)