I just came upon a 1980 NC50 and after a few days of work, got it to run today. My guess is that it is the first time it had run in five to ten years. When it started, it was bogging hard, spitting oil from the exhaust, and when I shut it off, I noticed it was dripping from where exhaust meets combustion chamber. There is also oil in the combustion chamber, I then realized. Not good.
It is very much a project bike, but I am wondering what's next.