Smallbore Class
Up to 185cc two stroke (2T) or 200cc four stoke (4T).
250 4T permitted for 125 Classic Class only. Must be 250cc (no big bores)
Midbore Class
Up to 250cc two stroke (2T) or 400cc four stoke (4T)
Open/Bigbore Class
251 and over two stroke (2T) or 401cc and over four stoke (4T)
Overs
201cc and greater
Unders
0 - 200cc