Build Your Own MA Historic Period 3 Machine:


Historic Period 3 Solo is the premier class in historic racing. Themachine in the left photo is a 'replica' of the 1950s ESO racer (right photo), and is currently racing in Victoria. For anyone interested in starting in an historic class, and becoming really competitive, this type ofmachine offers the simplest route. An example ofMA Historic Period 3 racing can be seen at : http://www.youtube.com/watch?v=D-bHE03ARxA Most Period 3machines can be raced inMA Historics, BEARS, and FX Pro thunderbikes.
AUTHENTICITY
Before attempting to build an historic racingmachine the Motorcycling Australia General Competition Rules should be consulted. Authenticity ofmachines is controlled by the Motorcycling Australia Historic Commission through log books.
BUILDING THEMACHINE
NortonManx replica frame and tanks are available for about $3000. A 500cc two valve Jawa speedway enginemay be sourced from Europe or Australia for about $3000. A return oil pump is available locally. A Triumph pre-unit gearbox, offers the option of five gears, and a close ratio modification is available from the UK. A Grimeca drum brake offers an economical alternative to amajor requirement. The rest of themachinemay be built from parts sourced from the wreckers. It is then amatter ofmanufacturing engine plates and brackets. The Jawa motor is almost identical to that of the 50s ESO racer, and has the advantage that it is a genuine racing motor, whereasmanymachines currently racing are based on old British touringmachines, with attendant problems.
Build Your Own MA Historic Period 4Machine
There aremany options to get started in Motocycling Australia Historic Period 4. For the ambitious there are a few useful Britshmachines which can be built as replicas ofmachines which existed in the era. Replica Seeley frames can be purchased from the UK, and a Norton Commando engine and gearbox used to build a Gus Kuhn Norton 750 Replica


. An example of such amachine can be seen being tested at:
http://www.youtube.com/watch?v=S509LGFabCw
And being raced at:
http://www.youtube.com/watch?v=funNlm0XIFE
The Two Stroke Option
A sensible option for a newbie is buy a 60s Yamaha two strokemachine, and modify it. A Suzuki T250 is cheaper, however the engine technology is different. It is not possible to make a Suzuki into the euivalent of a Yamaha, using the same port dimensions and timings. However good results may be achieved. if restraint is used. The tranfser port timing is critical, and a radical exhaust port timing will move the power band above the useful rev range, causing the motor to self-destruct. It is advisable to use T20 Suzuki connecting rods with T20 pistons. This allows a wider inlet port, and a safer piston and rod combination. A successful alcohol fuelled project is shown below blitzing a Yamaha TZ350G at Ballarat Airstrip. This machine was passed to Ian Whitehead of the Hartwell Motorcycle Club who won 23 races and 5 championships with it.

The two machines shown are Yamaha two strokes. The one on the left is a TZ350G GP machine. THe one on the right is an RD250LC street machine. The two machines s hould not be confused with each other. A TZ 350G in the hands of a competent rider, is a force to be reckoned with, in any MA Historic Period 5 race - it is also extremely expensive to race! The machine on the right is suitable for beginners wanting to race in MA Historic Period 5 . An additional front disc brake and caliper should be fitted, decent tyres, and it is wise to forego any extra modifications, except removal of the usual street gear- mirrors, and lights. For those wis hing to compete in MA Historic Period 6, a Yamaha RZ350 is a good option, but the 350cc versions of both water cooled RD and RZ Yamahas are difficult to find. It is not wise to try to develop a street machine into a racer. For an expert rider, a good TZ350 with a spares kit will probably be less expensive in the long run

USEFUL LINKS
The following is a list of useful links when preparing a classic racingmachine:
Drum Brakes:
http://victorylibrary.com/brit/2LS-table.htm
Computime
Two Stroke Expansion Chambers
Bucket Racing
http://huntertoolup.com.au/forum/viewforum.php?f=2
SteveManey Norton
http://www.stevemaney.com/products.html
TT Industries Gear Box
http://www.ttindustries.com/index.html
Moto Tumbi Fibreglass
http://www.classic-motorcycle-fiberglass.com/
Norton Commando
http://www.accessnorton.com/post30035.html
Britbike Forum