Model:
Commando 750/850, Atlas, G15CS, N15CS, P11
Model Years Covered:
1966-1976
Engine Codes:
750cc parallel twin, 850cc parallel twin
Model Codes:
Atlas, Commando (various sub-models), G15CS, N15CS, P11
Positioning:
Essential technical documentation for owners and technicians of classic British motorcycles, specifically Norton models from the mid-60s to mid-70s. Targets enthusiasts focused on restoration, maintenance, and performance tuning.
Value Proposition:
Provides instant access to dealership-level repair information, eliminating shipping delays and the need for expensive physical manuals. Offers cost savings compared to physical reproductions or official factory manuals.
Accessibility:
Instant digital download for immediate use on PC or Mac. Printable format allows for flexible use in a workshop environment.
Completeness:
Covers a wide range of models and years within the specified period, offering a comprehensive resource for most maintenance and repair tasks.
Primary Coverage:
Service, Repair, Workshop
Secondary Coverage:
Maintenance, Troubleshooting, Technical Specifications
Estimated Pages:
Varies by specific model/year, but comprehensive (typical workshop manuals for this era can range from 200-500+ pages)
Type:
Workshop Service Repair Manual
Format:
Adobe Acrobat PDF
Engine:
Complete engine overhaul, top-end rebuild (cylinder heads, valves, camshafts), bottom-end rebuild (crankshaft, connecting rods, pistons), lubrication system, cooling system (if applicable to specific models), fuel system (carburetors, fuel lines), ignition system (magnetos, coils, spark plugs)
Transmission:
Gearbox disassembly and assembly, clutch operation and adjustment, gear shifting mechanisms, oil specifications and procedures
Chassis:
Frame inspection and repair, suspension (front forks, rear shocks), steering system (headstock bearings, linkages), wheel and tire maintenance, braking system (drum brakes, disc brakes, hydraulic components)
Electrical:
Wiring diagrams for all models, lighting system (headlights, taillights, indicators), charging system (alternator, rectifier/regulator), battery maintenance, ignition timing, troubleshooting electrical faults
Frame Fuel System:
Fuel tank servicing, fuel lines, petcock maintenance, frame alignment checks
Locks Seats Battery:
Ignition switch servicing, seat removal and installation, battery charging and replacement procedures
Maintenance:
Regular servicing, oil changes, filter replacements, chain adjustment, brake adjustments, carburetor synchronization, valve clearance checks
Repair:
Component disassembly, cleaning, inspection, repair, and reassembly for all major vehicle systems. Specific procedures for common wear items and potential failure points.
Troubleshooting:
Systematic diagnostic procedures for identifying and resolving common mechanical and electrical problems, often with symptom-based flowcharts.
Depth:
Comprehensive, suitable for professional mechanics and skilled DIY enthusiasts. Covers detailed specifications, tolerances, and rebuild procedures.
Digital Format:
PDF (Adobe Acrobat)
Printability:
High-resolution, optimized for clear printing of text and diagrams. User can print specific sections or the entire manual.
Binding Recommendation:
User printable for 3-ring binders or professional binding.
Recommended Paper:
Standard office paper for printing. Specific sections exposed to grease might benefit from laminated or cardstock printing.
Type:
Parallel-twin, four-stroke
Displacement 750:
743 cc (45.3 cu in)
Displacement 850:
848 cc (51.7 cu in)
Bore X Stroke 750:
Approximately 70 mm x 96 mm (varies slightly by specific Commando variants)
Bore X Stroke 850:
Approximately 73 mm x 100 mm (varies slightly by specific Commando variants)
Horsepower 750:
Approx. 50-60 bhp @ 6500-7000 rpm (depending on tuning and specific model)
Horsepower 850:
Approx. 55-65 bhp @ 6200-6800 rpm (depending on tuning and specific model)
Torque 750:
Approx. 45-50 lb-ft @ 4500-5500 rpm
Torque 850:
Approx. 50-55 lb-ft @ 4000-5000 rpm
Carburetion:
Typically twin Amal Concentric carburetors (e.g., 30mm or 32mm). Specific jetting and settings are detailed in the manual.
Fuel Type:
Premium Unleaded Gasoline (Octane rating appropriate for the era and compression ratio, typically 91-95 RON)
System:
Wet sump lubrication with oil scavenging pump. Oil capacity is typically around 4-5 pints (2.3-2.8 liters).
System:
Typically Lucas Magneto ignition or battery-coil ignition depending on the specific model and year. The manual will cover timing and maintenance for both.
Type:
4-speed constant mesh gearbox
Gearbox Variants:
Some later models or aftermarket modifications might feature 5-speed gearboxes, though the primary coverage will be 4-speed.
Clutch:
Wet multi-plate clutch. Manual covers adjustment, friction plate replacement, and primary drive chain maintenance.
Gear Ratios:
Specific gear ratios for each model and variant will be detailed within the manual.
Transmission Oil:
Typically SAE 20W-50 or 10W-40 motorcycle gear oil. Manual will specify exact type and capacity.
Safety Standards:
As a manual for vintage motorcycles, explicit crash safety ratings are not applicable in the modern sense. The manual will focus on safe operation and maintenance of braking and steering systems.
Braking System:
Front and rear drum brakes or front disc brake (later models). Manual provides detailed procedures for adjustment, relining, and hydraulic system maintenance for disc brakes.
Chassis Integrity:
Emphasis on frame inspection for cracks or damage, and proper tightening of critical fasteners. Correct suspension setup for stable handling.
Oil Change:
Typically every 3,000 miles (5,000 km) or annually, whichever comes first. Manual will provide exact recommendations.
Valve Adjustment:
Recommended every 6,000 miles (10,000 km) or as per manual's specifications. Critical for maintaining performance and preventing engine damage.
Chain Adjustment:
Regularly, especially if riding in wet conditions or with a passenger. Typically 0.5-1 inch (12-25 mm) of slack.
Carburetor Sync:
Recommended periodically, especially if the engine runs rough or if carbs have been serviced.
Engine Oil:
SAE 20W-50 motorcycle oil is commonly recommended for these engines. Manual will confirm specific viscosity and API classification.
Brake Fluid:
DOT 3 or DOT 4 hydraulic fluid for disc brake models. Manual will specify.
Isolastic Wear:
The rubber bushings in the Isolastic system can wear over time, leading to increased vibration and imprecise handling. Manual covers inspection and replacement.
Transmission Leaks:
Commonly experienced oil leaks from gearbox seals and the primary drive chaincase. Manual details seal replacement.
Electrical Gremlins:
Lucas electrical components of this era are known for reliability issues. The manual's detailed wiring diagrams and troubleshooting guides are invaluable.
Carburetor Issues:
Amal carburetors can be finicky; wear in the slide, needle jet, and throttle shaft can cause poor running. Manual covers tuning and rebuilding.
Engine Mount Bolts:
Importance of correctly torqued engine mounting bolts (especially the Isolastic system) for vibration damping and chassis integrity.
Heritage:
Norton is a legendary British motorcycle manufacturer with a rich racing heritage, known for innovations like the featherbed frame and the Commando's 'Isolastic' engine mounting system designed to reduce vibration.
Commando Development:
The Commando evolved from the Atlas and featured the Isolastic system, significantly improving rider comfort and handling. It went through various iterations (Fastback, Roadster, Interstate, Combat, John Player Special) and engine sizes (750cc and 850cc).
Atlas History:
The Atlas was the predecessor to the Commando, using the earlier Dominator engine in a lighter frame, but was known for its vibration issues.
G15Cs N15Cs P11:
These models represent Norton's off-road and scrambler variants, often featuring higher handlebars, different suspension, and knobbier tires. They share many engine and transmission components with road models but have specific chassis and bodywork differences.
Production Period:
The period covered (1966-1976) represents the peak and later years of Norton's independent production before various ownership changes and eventual cessation of classic model production.
Model Reputation:
The Norton Commando is widely regarded as a classic British motorcycle icon, celebrated for its performance and handling in its day, despite some inherent reliability challenges.
Racing Success:
Norton motorcycles, including models based on the Commando engine, achieved significant success in various racing disciplines, including endurance racing and Isle of Man TT races, contributing to the brand's legend.
