Hi, what part of Taiwan are you in? I used to live there and I had a Kymco NSR. It's actually a Japanese design - Honda made the first NSR150s in Taiwan, in partnership with Kymco, then Kymco took over the production after the first year. As such, the first generation Japanese engines are quite sought after in NSR circles.

Anyway.

It shouldn't be doing the idle thing like that. Mine would do that sometimes before I got it sorted out, it was a carb issue if I remember correctly. My powervalve didn't work and was permanently open.