Stihl 201 spark arrester plugged

Carbon build up is a problem I see with users not running Aspen fuel here. Not so often as 90% of users here run Aspen.
Oil is the key, but fuel, settings, handling and saws engine design has a lot to do with it.
http://chainsawcollectors.se/phpbb3/viewtopic.php?f=124&t=29678