Target Audience:
DIY motorcycle mechanics, BMW enthusiasts, and professional workshops specializing in air-cooled BMW boxers.
Value Proposition:
Provides essential, in-depth technical information for maintaining and repairing the iconic BMW R-series models, empowering owners to perform their own servicing and complex repairs.
Diy Focus:
Detailed, step-by-step instructions tailored for home mechanics.
Original Documentation:
Likely based on or derived from official BMW factory service literature of the era.
Engine Mechanical:
Engine disassembly, assembly, inspection, repair, tuning, valve adjustment, piston/ring replacement, crankshaft/connecting rod procedures, timing chain inspection and replacement.
Fuel System:
Carburetor overhaul (Bing), fuel pump operation and testing, fuel tank maintenance, fuel line inspection.
Ignition System:
Ignition timing adjustment, spark plug selection and replacement, coil testing, ignition module troubleshooting.
Transmission:
Gearbox disassembly, assembly, inspection, clutch service (single plate dry clutch), gearbox oil change and specification.
Drivetrain:
Final drive unit inspection and service, driveshaft U-joint inspection, wheel bearing replacement.
Brakes:
Brake system maintenance, brake fluid replacement, caliper overhaul, brake pad/shoe inspection and replacement, brake line inspection.
Suspension:
Fork service (front suspension), rear shock absorber inspection and replacement, swingarm bearing service.
Electrical System:
Wiring diagrams, battery maintenance, charging system (alternator/generator), starter motor, lighting circuits, instrument cluster troubleshooting.
Frame And Bodywork:
Frame inspection, fairing and body panel removal/installation, seat maintenance.
Basic Maintenance:
Oil and filter changes, spark plug checks, chain lubrication and adjustment, brake fluid checks, tire pressure checks.
Troubleshooting:
Diagnostic flowcharts for common running issues, electrical faults, and starting problems.
Major Repairs:
Engine rebuilds, transmission overhauls, fork seal replacement, carburetor synchronization.
Electrical Diagnostics:
Testing electrical components, diagnosing wiring faults, using multimeters.
Engine Tuning:
Carburetor synchronization, idle speed adjustment, ignition timing setting.
Chassis Maintenance:
Wheel bearing inspection and replacement, steering head bearing adjustment, swingarm lubrication.
Electrical Component Testing:
Testing of starter motor, ignition coils, headlight switch, and other electrical switches and components.
Depth:
Comprehensive. Covers everything from routine maintenance to full engine and transmission rebuilds, including detailed diagnostic procedures and torque specifications.
Diagnostic Charts:
Includes detailed troubleshooting flowcharts for common performance issues.
Torque Specifications:
Comprehensive list of torque values for all critical fasteners throughout the motorcycle.
Wiring Diagrams:
Detailed electrical wiring schematics for accurate diagnosis and repair of electrical systems.
Engine Type:
Air-cooled, four-stroke, boxer twin-cylinder engine.
Displacement R80:
797.5 cc (approx. 800cc)
Displacement R90:
897.2 cc (approx. 900cc)
Displacement R100:
979.9 cc (approx. 1000cc)
Valve Train:
Overhead camshaft (OHC) driven by a timing chain.
Bore Stroke R80:
90.0 mm x 62.0 mm
Bore Stroke R90:
90.0 mm x 70.6 mm
Bore Stroke R100:
94.0 mm x 70.6 mm
Compression Ratio Typical:
8.2:1 to 9.5:1 (varies by model variant)
Horsepower R80:
Approx. 50 HP @ 6,500 RPM
Horsepower R90:
Approx. 65 HP @ 7,000 RPM
Horsepower R100:
Approx. 70 HP @ 7,000 RPM
Torque R100:
Approx. 77 Nm (57 lb-ft) @ 5,500 RPM
Carburetors Type:
Dual Bing constant-velocity carburetors (e.g., 32mm or 40mm depending on model).
Fuel Type:
Unleaded gasoline, minimum 91 octane (RON+MON)/87 AKI recommended.
Oil Change Interval:
Every 5,000-10,000 km (3,000-6,000 miles) or annually, whichever comes first (refer to manual for exact specs).
Valve Adjustment Interval:
Typically every 10,000-20,000 km (6,000-12,000 miles).
Gearbox Oil Change Interval:
Every 10,000-20,000 km (6,000-12,000 miles).
Engine Oil Capacity:
Approx. 2.0 - 2.5 liters (5W-40 or 10W-40 motorcycle specific oil recommended).
Brake Fluid Spec:
DOT 3 or DOT 4 brake fluid.
Final Drive Oil Spec:
Typically SAE 80W/90 GL-5 gear oil.
Oil Leaks:
Common leaks from cylinder head gaskets, pushrod tube seals, and transmission output shaft seals.
Clutch Wear:
The dry clutch can wear over time and require replacement.
Charging System Reliability:
Early models could experience voltage regulator or alternator output issues.
Carburetor Tuning:
Bing carburetors require periodic synchronization and adjustment for optimal performance.
Fork Seal Leaks:
Front fork seals can degrade over time and require replacement.
Bmw Motorcycle Legacy:
BMW has a long and storied history in motorcycle manufacturing, dating back to the early 20th century, renowned for its engineering prowess and boxer engine configurations.
Airhead Boxer Development:
The R80, R90, and R100 models are part of the 'Airhead' lineage, evolving from earlier boxer twins with significant updates in engine performance, chassis, and braking systems throughout the 1970s and 1980s.
Production Era:
The R100 series, including variants like the R100/7, R100S, R100RS, and R100RT, were produced from the mid-1970s through the early 1990s. The R80 and R90 series also had their production runs within this general timeframe.
