We are asked about the Sideburn-sponsored DTRA Vintage class regs from time-to-time, so we asked the DTRA to share their guidelines. This is what they said.
The DTRA Vintage class is broad, but with all motorcycles reflecting a certain 'spirit of the age'. Before you race you will need to get your bike choice approved by the club. But as a guide;
First quideline is pre-1975
All bikes must be twin shock, or if it’s really early, rigid. No monoshocks.
Vintage bikes need to look like a flat tracker in stance (not just an old MX bike) and be mechanically sound.
Your bike will take a lot of punishment, so don’t just drag that leaking Bonnie or hanging RM250 out from the shed and expect to race.
Four-stroke Vintage: No overhead cam engines, British is obviously popular. The class already includes some street trackers, some full-bore ‘Framer’ old school race bikes imported from the US and some shed build racers. No cc limit.
Two-stroke Vintage: Air-cooled only, probably no later than early-70s. CC limit decided by your bravery.
Please contact the club if you have any doubts.
Four-strokes and two-strokes run together in the same heats and finals, but are scored separately, have their own podiums and championships.
UPDATE
Tyres: While all other DTRA adult classes have demanded dirt track-specific tyres, and the DTRA have set a control tyre that must be used in those classes, the Vintage classes have never had to comply. Some bikes in the class don't have enough clearance to run modern flat track tyres, though the majority of the class do use them. Some riders choose trials/speedway tyres that give something of an advantage on certain surfaces. Knobblies are not permitted.
There will not be a control tyre in any DTRA class for 2021, but it might return in the future. All tyre must be recognised as DT specific - Dunlop, Maxxis, Shinko, Mitas...
Check out this Vintage DTRA megapost to see some great photos from the class.