| 50cc Standard | Y1 | 6-9 | 50cc, no power mods, Auto |
| 50cc Modified | Y1 | 6-9 | 50cc max 2T, 112cc max 4T, no engine mods 4T. Autos only |
| 100cc Standard | Y2 | 8-13 | 100cc 2T, 150cc 4T, manufacturer build, Auto |
| 100cc Modified | Y2 | 8-13 | 100cc 2T, 150cc 4T, Auto |
| 100cc Geared Air Cooled | Y2 | 8-13 | 119cc 2T, 179cc 4T, air cooled |
| 100cc Geared Water Cooled | Y2 | 8-13 | 119cc 2T, 179cc 4T, water cooled |
| 150cc Open Geared | Y3 | 11-16 | 119cc 2T, 179cc 4T, race with 250s |
| 250 Standard | Y3 | 11-16 | 200cc 2T, 250cc 4T, no power mods |
| 250 Modified | Y3 | 11-16 | 239cc 2T, 299cc 4T, air cooled production only |
| 250 Open | Y4 | 11-17 | 239cc 2T, 299cc 4T, air cooled production only |
| Novice | Adult | 15+ | 450cc, only by prior agreement with club |
| Clubman | Adult | 15+ | 550cc 2T 2 cyl, 800cc 4T 1 cyl |
| Seniors | Adult | 40+ | 550cc 2T 2 cyl, 800cc 4T 1 cyl |
| Adult Championship | Adult | 15+ | 550cc 2T 2 cyl, 800cc 4T 1 cyl |