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Manual Coverage
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Systems Covered
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Engine:
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Full coverage including disassembly, assembly, tuning, troubleshooting.
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Transmission:
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Clutch, gearbox (internals and external components), chain drive.
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Brakes:
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Front and rear brake systems (drum and potentially early disc), hydraulic and mechanical actuation.
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Electrical System:
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Ignition system, lighting, charging system (alternator/generator), wiring diagrams, battery, starter.
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Suspension:
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Front forks (telescopic), rear swingarm, shock absorbers, steering head bearings.
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Fuel System:
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Carburetor(s) (likely Amal Concentric), fuel tank, fuel lines, petcock.
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Exhaust System:
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Exhaust pipes, mufflers, mounting hardware.
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Frame And Bodywork:
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Chassis inspection, frame repairs, mounting points, body panels.
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Wheels And Tires:
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Spoke wheels, rim maintenance, tire fitment, balancing.
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Procedures Included
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Maintenance:
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Oil changes, filter replacements, chain adjustment, lubrication points, spark plug replacement.
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Troubleshooting:
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Diagnosis of common running issues, electrical faults, starting problems.
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Repair:
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Detailed step-by-step instructions for component replacement and repair.
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Rebuild:
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Complete engine rebuild, gearbox overhaul, fork rebuild.
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Tuning:
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Carburetor adjustment, ignition timing, valve clearance.
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Technical Depth
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Depth:
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Comprehensive, covering everything from basic maintenance to complete engine and gearbox rebuilds.
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Diagnostic Capability:
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Detailed troubleshooting guides and symptom-based problem solving.
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Precision Specifications:
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Includes torque settings, clearances, fluid capacities, and tolerances.
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Engine Specifications
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Primary Engine
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Type:
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Parallel-twin, air-cooled, pushrod overhead valve (OHV)
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Displacement:
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798 cc (48.7 cu in)
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Bore X Stroke:
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73 mm x 93 mm (2.87 in x 3.66 in)
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Compression Ratio:
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Typically 8.5:1 to 9.2:1 depending on specific model/tuning
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Power Output Hp:
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Approx. 50-55 bhp @ 6,000 rpm (varies by model and tuning)
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Torque Lb Ft:
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Approx. 48-50 lb-ft @ 4,000 rpm (varies by model and tuning)
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Fuel System
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Carburetor:
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Typically one or two Amal MkII Concentric carburetors (e.g., 30mm or 32mm).
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Fuel Type:
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Unleaded gasoline (91 RON or higher recommended, consult manual for specific octane recommendations for the era)
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Ignition System
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Type:
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Coil and points ignition (Lucas or similar) or Boyer-Bransden electronic ignition (aftermarket/upgrade).
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Maintenance
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Service Intervals
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Oil Change:
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Typically every 2,000-3,000 miles or 6 months.
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Valve Clearance Check:
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Recommended every 3,000-4,000 miles.
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Chain Adjustment:
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As needed, typically every 500-1,000 miles, checking for slack.
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Fluid Specifications
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Engine Oil:
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SAE 20W-50 (e.g., Castrolite or equivalent motorcycle-specific oil). The Commando shares engine oil with the gearbox and primary drive.
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Gearbox Oil:
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Same as engine oil (SAE 20W-50). Some sources may recommend specific gear oil additives.
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Brake Fluid:
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DOT 3 or DOT 4 (for disc brake systems).
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Fork Oil:
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Typically SAE 5W or 10W fork oil. Capacity is crucial and specified in the manual.
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Known Issues
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Engine Vibrations:
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Characteristic high vibrations, especially at certain RPM ranges, were a hallmark of the Commando engine. Rubber-mounted engine isolates the rider from some of this.
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Oil Leaks:
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Common from various seals and gaskets over time due to age and material degradation.
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Electrical Reliability:
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Lucas components could be temperamental; routine checks and maintenance of wiring and connections are vital.
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Gearbox Shifting:
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Some models could be prone to false neutrals or stiff shifting if not properly maintained or adjusted.
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