china 2 strokes are either 49cc or 66cc. the "80" is just a myth.
there's no serial numbers, and without the metal tag, no dates.
the 66 is obviously bigger, and the 49 usually has a more rounder head.
post a pic and someone can ID it.
mixture should be either 24:1 or 32:1 on a broken in engine with regular 2 cycle oils.