I'm not on face book so I couldn't post, in the early day's of Forgotten Era there were 2 classes within the races, twin cylinder & multi cylinder.
Both classes ran 4 stroke & 2 stroke engines. There was a specific ban on Jap multi 4 stroke & 2 stroke engines, ie, TZ700, GS1000 etc.
There was "special dispensation" for certain engines like the Barton Pheonix.
Then the jap multis were let in & that rang the death bell for the class.