The classes have changed over the years with bike changes.
I think they have a 125-200cc class on CRA which is usually competitive. If you race the AMA Nationals, they will have B classes pretty sure.
Depending on your age, you can run a vet class. Thinking +30 is the first Vet class locally in HS.
You can go to
www.racecra.org for their class structure.
You may also want to check out GP's with Action Sports by Mr. Wolfe.
I LOVE the woods!