When I used to race dirt bikes, some guys would have to change the rings after putting about 10-15 hours on their engine. The big ports just wore the rings out fast. I don't think most loggers or arborists would want to have to change rings every other work day just for the pleasure of having a 20hp 80cc saw.
Also, when that guy Simonizer was on this group, he was saying something about the crankcase in most saws was too small to allow for high HP. I'm not sure exactly why he said this but it's true that the crankcases on dirtbikes are bigger for a similar displacement (look at the crankcase on an 80cc dirtbike cersus an 80cc chainsaw). Dirtbikes also have tuned pipes, bigger carbs and water cooling to remove the excess heat that high power output generates.
Also, when that guy Simonizer was on this group, he was saying something about the crankcase in most saws was too small to allow for high HP. I'm not sure exactly why he said this but it's true that the crankcases on dirtbikes are bigger for a similar displacement (look at the crankcase on an 80cc dirtbike cersus an 80cc chainsaw). Dirtbikes also have tuned pipes, bigger carbs and water cooling to remove the excess heat that high power output generates.