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Dunstall Motorcycles
1973 Dunstall Norton 850 Mk 4


1973 Dunstall Norton 850 Mk 4

The ultimate in motor cycling pleasure by Paul Dunstall. Like the 850 Mk 2 and 3 it features a special Dunstallised Cylinder Head which improves efficiency and gives better performance throughout the range. Exact details of the modification can be found in the Brief specification. Like all Dunstall Nortons it is smooth and vibration free. It is also flexible and can be pottered along at slow speed when necessary. It really comes into its own on fast open roads when its performance and handling can be used and enjoyed to the full. The twin hydraulic Disk Brake is of course the outstanding feature on this machine.

Brief Specification

  • Capacity 830 cc
  • Re-Sphered & Machined Combustion Chambers
  • Steeper Valve Angle (Inlet) 26½
  • Enlarged Hand Finished & Polished Ports
  • Special H 18 S Material Valves 1.5/8" Inlet
  • Bronze Hi-Dural Valve Guides
  • Enlarged Induction Manfolds
  • 10 to 1 Compression Ratio
  • Power Exhaust System
  • Dunstall Centre Stand
  • Decibel Silencers
  • Dural Silencer Mounts
  • Twin Disk Hydraulic Front Brake 10"
  • Alternative Dunstall Fairing featuring Direction Indicators (necessary for U.S.A.) colour choice Red, Yellow, Blue, Black
  • Rear Mounted Footrest Controls
  • 5 U.S. Gallon Tank colour choice Red, Yellow, Blue, Black
  • Glass Fibre Front Mudguard
  • Clip On Handlebars
  • Overall Gearing 4.15
  • Polished Alloy Wheel Rims

www.woodgate.org/dunstall/73nor4.html / Webmaster / Revised 24th February 2000