🏷️ Basic Information Identification Make: BMW Model: R80 GS / R100 GS Year: 1981 Engine Code Primary: Type 247 (Boxer Twin) Generation Gs Model Designation: First generation of BMW's 'Gelande/Strasse' (Off-road/Street) dual-purpose motorcycles Codes Chassis Type: Paralever (introduced later, but manual likely covers precursor frame designs and early single-sided swingarm) 👋 Introduction Market Position Segment: Dual-sport / Adventure motorcycle Target Audience: Owners of BMW R80 GS and R100 GS motorcycles seeking to perform their own maintenance and repairs, enthusiasts, and professional motorcycle mechanics. Competitive Analysis Market Competitors Era: Honda Transalp, Yamaha XT600, Kawasaki KLR600, Suzuki DR600, Moto Guzzi V50/V75 (less direct competitors) Key Features Motorcycle Design Philosophy: Robustness, versatility for on-road and off-road use, shaft drive for low maintenance, boxer engine's low center of gravity. Manual Value Proposition: Provides essential, professional-level technical information crucial for maintaining these classic and capable machines, ensuring longevity and optimal performance. 📋 Manual Details Coverage Areas Primary Coverage: Comprehensive service and repair for BMW R80 GS and R100 GS models Secondary Coverage: Maintenance, troubleshooting, diagnostics, and general overhaul Page Count Estimated Pages: 300-500 (typical for comprehensive workshop manuals of this era) Manual Type Type: Workshop Manual / Service Manual / Repair Manual Language Language: English Format Format: PDF Download File Format: PDF Print Quality: High-resolution scans, clear text and diagrams, suitable for printing Binding Type: N/A (Digital Download) Paper Type: N/A (Digital Download) Searchability: Likely text-searchable PDF for quick information retrieval 📖 Manual Coverage Systems Covered Engine: Detailed disassembly, assembly, inspection, and repair of the boxer twin engine, including cylinder head, valves, piston, crankshaft, camshaft, timing chain, oil pump, lubrication system, and cooling (air-cooled). Fuel System: Carburetor systems (likely Bing CV carbs), fuel tank, fuel lines, fuel pump (if applicable), and fuel filtering. Ignition System: Ignition timing, coil, spark plugs, distributor (if fitted), electronic ignition components, and troubleshooting. Transmission Drivetrain: Clutch operation and adjustment, gearbox (5-speed), final drive, and shaft drive maintenance. Suspension: Front fork (telescopic, likely leading axle design) overhaul, seals, oil, and rear shock absorber (Monolever or early twin shocks depending on specific 1981 sub-models) adjustment and replacement. Brakes: Front and rear brake system inspection, fluid replacement, caliper overhaul, disc and pad maintenance, and hydraulic system bleeding. Electrical System: Wiring diagrams, battery maintenance, lighting system, starter motor, alternator, regulator, and instrument cluster troubleshooting. Chassis Frame: Frame inspection, fork head bearing adjustment, swingarm bearing maintenance, and general chassis component checks. Bodywork: Fairings, fuel tank, seat, fenders, and minor body panel removal/installation. Procedures Included Routine Maintenance: Oil changes, filter replacements, spark plug checks, air filter cleaning, chain lubrication and adjustment (if applicable for early models), brake checks, tire pressure, and lubrication points. Troubleshooting: Systematic diagnostic procedures for common starting, running, electrical, and mechanical issues, often presented in a 'problem-cause-solution' format. Engine Rebuild: Step-by-step instructions for engine disassembly, cleaning, inspection for wear, measurement of critical components, part replacement, and engine reassembly with torque specifications. Transmission Overhaul: Detailed procedures for gearbox disassembly, gear inspection, bearing replacement, and reassembly. Suspension Fork Rebuild: Instructions for replacing fork seals, springs, and oil, including proper disassembly and reassembly. Electrical Diagnostics: Guidance on using multimeters, interpreting wiring diagrams, and troubleshooting electrical faults in the charging, ignition, and lighting systems. Carburetor Tuning: Steps for adjusting idle speed, mixture, and synchronization of dual carburetors for optimal performance. Technical Depth Depth: Comprehensive; covers everything from basic rider maintenance to full engine and transmission rebuilds, including detailed technical specifications and tolerances. Precision Measurements: Includes critical measurements and tolerances for engine components (e.g., bore, piston clearance, valve seat runout, bearing play) requiring precision measurement tools. Torque Specifications: Extensive torque values for all critical fasteners across all systems. ⚙️ Engine Specifications Primary Engine Engine Type: Air-cooled, horizontally opposed twin-cylinder (Boxer) Bore X Stroke R80: 81 mm x 70.6 mm Bore X Stroke R100: 94 mm x 70.6 mm Displacement R80: 797.5 cc Displacement R100: 979.7 cc Compression Ratio Typical: 8.2:1 to 9.5:1 (varies by specific sub-model and year) Performance Horsepower R80 Approx: 50 PS (37 kW) at 6500 rpm Horsepower R100 Approx: 65 PS (48 kW) at 7000 rpm Torque R80 Approx: 57 Nm (42 lb-ft) at 5000 rpm Torque R100 Approx: 70 Nm (52 lb-ft) at 5500 rpm Fuel System Carburetors: 2 x Bing 32mm CV (Constant Velocity) or similar Fuel Type: Unleaded gasoline (91 RON / 87 AKI or higher recommended) Fuel Tank Capacity Approx: 19-20 liters (4.9-5.3 US gallons) 🔧 Transmission Standard Gearbox: 5-speed constant mesh, sequential gearbox Clutch: Dry, single-plate, diaphragm spring Final Drive: Shaft drive, single-sided swingarm (leading to Monolever in later iterations, but likely single-sided in 1981 models) Features Gear Ratios: Specific ratios detailed in manual (typical first gear ~2.4:1, top gear ~1.0:1) Transmission Fluid Spec: SAE 90 Hypoid Gear Oil (check manual for exact specification and capacity, typically ~0.75L) 📐 Dimensions Exterior Wheelbase Approx: 1440 mm - 1460 mm (56.7 -...