hi Stefan,
i bought a Cadet kart (minus engine and wheels) last week, so was looking to find a kart sprocket that would fit the existing sprocket carrier. They have them in Australia but not apparently in the UK. Consequently, next step is to use industrial sprockets, but these seem to have a small bore. Found ones with 3/4" bores so far, so looking for ones with larger bores. May possibly have to enlarge the bore to suit. Kart ones are still my preferred option though if i can find some.