Norton 850 Commando – Stage One High Performance Modifications
Download the complete PDF version using the green download button at the top right of this page for the original Norton service release covering Stage One high performance modifications for the 850 Model Commando. This factory technical document explains the changes required to convert a standard road specification 850 Commando toward a higher performance sports condition, including engine component replacement, machining work, tuning data and workshop setup guidance.
The service release covers replacement of the standard camshaft with the 063536 “SS” camshaft, piston crown modification, cylinder head machining to increase compression ratio, Amal velocity stack fitment and pushrod shortening needed to maintain correct rocker geometry after the cylinder head has been altered. Detailed technical drawings show the piston crown machining, combustion chamber reshaping, port changes and revised pushrod dimensions.
The document also provides ignition timing, valve clearance, carburettor and exhaust recommendations for the modified engine. A separate service tools section follows, illustrating specialist Norton workshop tools used for clutch service, seal fitting, timing pinion removal, valve guide work, exhaust lockrings, Isolastic assembly, bearing extraction and other major maintenance operations.
Contents Include
- 850 Commando Stage One high performance conversion overview
- SS camshaft replacement specification
- Piston crown machining requirements
- Cylinder head modification for increased compression
- Inlet and exhaust port reshaping details
- Pushrod shortening and rocker geometry notes
- Ignition timing, valve clearance and carburettor recommendations
- Factory technical drawings and modification dimensions
- Norton specialist service tools catalogue
- Illustrated workshop tools for clutch, timing, valve and Isolastic work
