The Big Bang Postie Project


The aim of this project was to create a 20+BHP Postie Bike that handled and stopped

The final dyno figure of 20.8 BHP was achieved with the following engine modifications:

  • Conversion to methanol fuel
  • Aftermarket Yoshimura 28mm down draft carburettor
  • Foam filter air pod
  • Pit bike oil cooler
  • Modified inlet manifold
  • New exhaust
  • Long stroke motor
  • Larger exhaust titanium valve
  • After market cam
  • Crankcase breather
  • Unrestricted CDi ignition black box
  • Modifications to improve the handling included:
  • Telescopic forks front wheel and disc brake from a pit bike
  • Swing arm from a pit bike
  • Replacement rear shocks
  • Race standard Unilli road tyres
  • The bike was re geared to run 16 / 35 gearing


Starting and idling – The bike starts first kick and ticks over normally

Accelerating from a standstill the bike pulls like a little train and easily achieves about 130kph. The last 1/3 of the throttle seems redundant as the machine has tremendous torque

Uphill the bike fails to notice inclines and in a straight line pulls powerfully

Handling: The bike stops effectively on the front disc alone. Around curves apart from the upright riding position the bike tips in beautifully and holds a perfect line. The stance is somewhat strange on the bike but once used to the riding position it becomes perfectly normal.

The only major concern riding this bike was pot holes in the road, the small wheels and tyres made larger pot holes a serious concern!!!

Total Project Cost: $3,750 – Including purchase of bike

 The Big Bang Postie Project