Re NSU Quickly, I bought one in 1966 second hand for £5. It was cream in colour and was a 2 stroke. Every 20 miles or so the plug became sooty and I had to stop, wait for it to cool, take it out, clean it with a wire brush and put it back. It went at a reasonable speed for a young lady who wanted independence and not to be tied to buses that finished before I was ready to go home. I sold it for a Honda 50 which was much more reliable.