VMX Classes

[adam.m]

Can someone point me in the right direction as far as a list/guidelines of VMX classes and requirements to be accepted into each class.
For example, Im building an XL500R which is an 82 model but runs a pre 80 engine. So what class would I qualify for ?
What kind of hybrids are allowed to run, eg later model frames/suspension with early engines ?

[Nathan S]

The rules are spelled out in the Motorcycling Australia Manual of Motorsport.

http://www.ma.org.au/index.php?id=1770

They are a bit difficult to understand/confusing at times, so here's the basics:

There's categories for pre-60, pre-65, pre-70, pre-75, pre-78, pre-85 and pre-90 dirt bikes - they're all fairly self explanatory, although it's worth remembering that it's "pre-xx" - so you need a 1977 or older model to be legal for the pre-78 class.
Evo is for bikes that have drum brakes, air cooling and non-linkage rear suspension, regardless of date of manufacture - so a 2002 DT175 is a legal Evo bike. In reality, the majority of bikes in Evo are pre-82ish, so the class broadly represents that era.

The bike's age is defined by its newest major component. For example, a 1984 model fitted with 1988 suspension is not legal for pre-85 (but is legal for pre-90).

There's a degree of 'fat' in the rules, particularly at club level. If an otherwise legal bike happens to turn up with a later model rear hub (for example) it is highly unlikely that anyone will raise an eyebrow.
Similarly, there's a lot of ambiguity in the details of the rules, which will be debated endlessly on these forums... (chances are, this thread will become one of those endless debates). Don't worry about those details for now. The answer to your question is simple:

An 82 XR500 is a pre-85 bike. The 1980 engine doesn't change that.

Welcome aboard.

[09.0]

The bike's age is defined by its newest major component.

In a nut shell.

[firko]

The bike's age is defined by its newest major component.

The most overlooked, ignored or misunderstood sentence in the rulebook.  e.g. A 1964 Triumph Metisse with a 1986 Honda CR500 engine becomes a pre 90 bike despite the age of the other components.

[Montynut]

Or in your case a 1979 design engine in a 1982 linkage rear suspension frame and running gear is a Pre85 bike. A 1980 XR/XL500 is an EVO bike as it did not have linkage suspension.

Even if you fitted a 1964 BSA engine it would still be a Pre85 bike.

Most clubs will have a 4 stroke and the Vinduro (no racing) world has no classes at this point.