I've heard that from a few Agracat dealers. I think most of them just don't know. I don't think they are making this up. I think they are told this by someone who doesn't know either. Kind of like "the blind leading the blind". That engine is not a Yanmar. It is a Yangdong. Like most Chinese engines, they are based on a combination of European design and some Japanese and Korean technology. If I was going to say it was the same thing as something else, I'd call it a Volkswagen or Utos, but that would be a stretch.
