The Rotax engine is assembled by Loncin in China! Just because a Chinese person assembled the engine doesn't make it a Chinese engine!
If you're using that as the yardstick, then if your Gay Harley engine was assembled by a Mexican guy in the factory then your bike is Mexican.
BMW, as I understand it, use the Chinese to assemble a lot of their engines.....including cars. But they are not Chinese engines as you well know.
"The new G650GS is essentially the 2007 single-cylinder F650GS brought back into production with some minor modifications and with the engine assembled by Loncin in China instead of Rotax in Austria, but still using parts manufactured by Rotax in Europe".
https://en.wikipedia.org/wiki/BMW_G650GS