It is one cylinder, air cooled (!), 5 hp. Has a traditional F-N-R gearbox.
I have seen a few for sale here in Finland, but there seems to be close to no info available on the internet, so if anyone knows anything about these engines please come forward!
This engine was given to me by the neighbor at my GF's summer cottage. He saw my HD-26 and JW-16 that I brought with me the last time we went there, and was so impressed by my work that he wanted to give me this engine (not bragging, I felt quite flattered!). It's in an overall good condition, seems not to have been run that much, it only really needs cosmetical work. But it is in a surprisingly good shape considering that it had sat outside for the last five years!
Immediately when I got it I started to tear it apart. Found that it had good compression and even spark, which is always nice. I cleaned the carburetor and it fired after just a couple of pulls! Luckily I cleaned the carb before trying to start it, since the carb was completely gummed up with something unidentifiable.