Jaka; The info I repeated concerning ringed vs. ABC came straight from a question I asked many years ago on RCO where it was answered by none other than George "Nobler" Aldrich who ranks right up there with Clarence Lee as being a virtual "engine god" in RC flying. But any one in the hobby, even a rank beginner, can simply feel the compression an ABC engine makes when new compared to a ringed engine of the same size.
George commented that there wee not many ABC 2 stroke glow engines once you got over the 60 size since the compression these engines usually have makes them more difficult to turn over and start. I think many on RCU knew of "Nobler" and what he said could always be taken to the bank - period.

The website you listed is in Swedish or some other language I could not decipher to in fact see if the big MVVS engines are not ringed as you say.