As in other countries Australian Historic Racing is divided up into Classes based on the age and engine capacity of the machine. The structure relevant to any Laverdas you might find on the track are as follows:

Categories (Machine Age)

Period 4 Post-Classic 1963-72
Period 5 Forgotten Era 1973-82
Period 6 New Era 1983-90

Classes (Machine Capacity)

Senior 368-500cc
Formula 750 526-750cc
Unlimited 526-1300cc

Various combinations and abbreviations of the above are often used, so for example you might find reference to PC or P4 for Post-Classic, FE or P5 for Forgotten Era, PCU for Post-Classic Unlimited, NE7 for Forgotten Era 750, etc.

What's Allowed and What Isn't?

In terms of modifications, Australia is fairly liberal. The quick bikes are often little more than a "sillouette" where the externals must resemble the model on which the bike is based, but much of the bike is completely re-engineered and re-manufactured.

"Major Components" (engine & gearbox castings, frames, swingarms, brakes, forks and fork yokes) should be from the period or "visually indistinguishable" from period components. Some latitude is allowed by the organisers and some creative interpretation is excercised by some entrants. :-)

Wheels and Tyres:

Period 3 must run 18" rims of a maximum width of 2.15", while Period 4 can use 18"x 2.5"- both must use treaded tyres although sticky race-specials are allowed. In the later Period 5 class, the 500cc machines can use 18" rims up to 2.5" front and 4" rear again with treaded tyres, while the Period 5 Unlimited bikes are allowed 17" rims of 3.5" front and 4.5" rear and slick racing tyres.


Period 3 & 4 are allowed to use Methanol fuel. Period 5 must use Unleaded Petroleum fuel of maximum 100 octane.

There are numerous gripes and the occasional protest or exclusion but things run pretty smoothly and in general I'd say Australian bikes tend to be more highly modified than many places.

The full rulebook can be viewed here.