In 2.4.1 Class displacement
Super Twins GTU is stated:
Up to 125cc single cylinder two stroke
Up to 750cc two cylinder four stroke
Unlimited displacement, two cylinder, two valves per cylinder, air cooled
consider adding:
Up to 650cc single cylinder four stroke
This would allow the small amounts of Colorado Class spec bikes another class to be in, and besides most of the grid is 650 twins that the singles race against in LWGP.