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Written by Vic R   

Engine Setup

  • Machine the top of the barrel to within .1mm of the legal exhaust port height.
  • Machine the bottom of the piston to within .1mm of the legal length.
  • To make the engine pull hard out of corners, set the barrel up as low as possible.
  • To make the engine rev a little harder, set the barrel up as high as the rules allow (1mm between top of barrel and top of piston)
  • Set ignition timing 2.8 mm for light driver 3.0mm for heavy driver.
  • Set pipe length to 925 for light driver and 935 for heavy driver.
  • Set pop off on carby to 9.5
  • Lever height 0.8 (without gasket)
  • CC head to 11.3cc's
  • Setup gearing to achieve between 10400 rpm for low barrel and 10800 rpm for high barrel. (min revs 6,000)
  • Mixture 18 to 1 (Castor/Synthetic such as Shell M100)
  • Spark Plug - Sydney 9 (winter) 8.5 summer, Brisbane 9.5
  • Max engine temp - 200C (prolong use at this temperature will lead to engine siezure)


  • If need to run-in, run Castrol R30 for first 100 laps.
  • The first two ten minute sessions should be at reduced revs.
  • If racing - new ring every 9 hours, new piston every 18 hours
  • Remove end cap and clean every three races. (Use Bi carb Soda (4 teaspoons per litre of water))


  • Start with long flex (945mm for heavy)
  • Start with low gearing gearing (more rear teeth).
  • Increase (less rear teeth) until lap times reduce
  • Once gearing is set, start reducing flex length (2 mm will make a difference)


  • Start with Low at 1 1/2 turns out
  • High at 1/4 turn out
  • During session - increase low to 1 3/4 (should not need to go higher than 2 turns if engine/carbie ok)