Well I have got one of the 30cc engines and it looks oK to me so far. It wasn't stuck, the bearings feel OK. I didn't see any obvious runout issues on the front hub either. But I'll need to check it later. So I guess it depends on how lucky you get like usual. I am in no hurry to get a 60cc twin as I already have a 55cc twin and I have a couple of 50cc and 56cc engines plus a 58cc liquid cooled engine and a 58cc air cooled engine too.

I still wonder how someone can tell if a certain individual was involved in the production of the engines myself. I didn't see any mention of who was making them, etc.