Positioning:
Essential technical resource for owners and technicians of BMW's iconic R-series airhead motorcycles from the 1981 model year.
Comparison:
Directly supersedes or complements official BMW factory service manuals for the specified models, offering a comprehensive, in-depth guide.
Distinctive Aspects:
Focus on the robust and well-engineered 'Airhead' boxer twin engine platform, renowned for its durability and distinctive character.
Usability:
Structured for efficient workflow in a workshop setting, with clear sectioning and detailed procedural steps.
Primary Coverage:
Service, Repair, Workshop
Additional Coverage:
Maintenance, Troubleshooting, Diagnostics
Estimated Page Count:
300-500 (typical for comprehensive workshop manuals of this era)
Type:
Workshop Manual / Service Manual
Target Audience:
Professional Mechanics and Experienced Enthusiasts
Format:
Print (implied by "manual" and typical sales of such products)
Powertrain:
Engine (R80, R90, R100 variants), Transmission, Final Drive
Chassis:
Frame, Suspension (Front forks, Rear swingarm), Steering
Brakes:
Front and Rear Brake Systems (Drum and Disc, depending on model/year)
Electrical:
Ignition System, Lighting, Charging System (Alternator, Battery), Starting System, Instrumentation
Fuel System:
Carburetion (Bing carburetors), Fuel tank, Fuel lines, Fuel pump (if applicable)
Exhaust System:
Exhaust headers, Mufflers, Clamps
Bodywork:
Body panels, Fenders, Seat, Fuel Tank, Fairings (if equipped)
Routine Maintenance:
Oil changes, Filter replacement, Spark plug maintenance, Valve adjustments, Carburetor synchronization
Major Repairs:
Engine rebuild, Transmission overhaul, Clutch replacement, Fork seal replacement, Shock absorber service
Troubleshooting:
Diagnostic procedures for common performance issues, electrical faults, and mechanical problems
Adjustments:
Carburetor tuning, Ignition timing, Clutch and brake lever adjustments, Suspension setup
Disassembly Assembly:
Step-by-step instructions for dismantling and reassembling major components
Depth:
Comprehensive: Covers routine maintenance to full engine and transmission rebuilds, including detailed electrical schematics.
Diagnostic Focus:
Strong emphasis on diagnostic procedures for common issues encountered by mechanics.
Format:
Printed, bound publication.
Quality:
High-quality print suitable for workshop environments, with clear diagrams and text.
Binding:
Stapled or perfect bound, designed for lay-flat use.
Paper Quality:
Durable paper stock, often with a laminated cover for protection against grease and fluids.
Type:
Four-stroke, air-cooled, horizontally opposed twin-cylinder (Boxer)
R80 Displacement:
797.5 cc
R90 Displacement:
897.2 cc (R90/6, R90S)
R100 Displacement:
979.7 cc (R100/7, R100S, R100CS, R100RT, R100RS, R100GS - though GS is later)
Bore Stroke R80:
82 mm x 74.5 mm
Bore Stroke R100:
94 mm x 70.7 mm
Compression Ratio Typical:
8.2:1 to 9.5:1 (depending on model)
R80 Horsepower Approx:
50 HP @ 6,250 RPM
R100 Horsepower Approx:
65 HP @ 7,000 RPM (R100RS/S)
R80 Torque Approx:
6.4 kg-m (63 Nm) @ 4,500 RPM
R100 Torque Approx:
7.5 kg-m (74 Nm) @ 5,500 RPM (R100RS/S)
Carburetors Type:
Dual Bing constant-velocity carburetors (e.g., 32mm for R80, 40mm for R100)
Fuel Type:
Unleaded gasoline (minimum 91 RON/87 AKI)
Fuel Delivery:
Gravity feed from fuel tank via fuel cock; some models may have electric fuel pump
Type:
5-speed constant-mesh manual gearbox
Type:
N/A (5-speed manual was standard across the range)
Drive Type:
Shaft drive to rear wheel
Clutch Type:
Single dry plate clutch, operated by cable
Gear Ratios:
Specific ratios detailed in manual, vary by model (e.g., R80, R100 series)
Crash Safety:
N/A (Motorcycle, no standardized crash ratings like cars; manual focuses on operational safety)
Braking System:
Single or dual disc front brake (depending on model), drum or disc rear brake. Manual covers brake fluid changes, pad/shoe replacement, caliper service.
Lighting:
Halogen headlight, taillight, brake light, turn signals. Manual covers bulb replacement and electrical diagnostics.
Frame Construction:
Steel duplex cradle frame. Manual covers frame inspection and potential repairs.
Oil Change Engine:
Typically every 6,000 km (3,700 miles) or annually. Manual will specify exact intervals.
Valve Adjustment:
Every 12,000 km (7,500 miles). Manual will detail procedure.
Carburetor Sync And Cleaning:
As needed, but often recommended with valve adjustments or at 12,000 km intervals. Manual provides guidance.
Brake Fluid Flush:
Every 2 years. Manual specifies fluid type and procedure.
Engine Oil:
SAE 20W-50 or SAE 10W-40 (depending on climate). Manual will list specific BMW or API/ACEA specifications.
Transmission Oil:
GL-5 80W/90 gear oil. Manual will confirm specification.
Final Drive Oil:
GL-5 80W/90 gear oil. Manual will confirm specification.
Brake Fluid:
DOT 4. Manual will confirm specification and replacement interval.
Common Wear Items:
Clutch wear, output shaft seal leaks, final drive spline lubrication, valve guide wear, carburetor float issues, fork seal leaks.
Electrical Quirks:
Loose connections, charging system issues (rectifier, regulator), aging wiring harnesses. Manual provides diagnostic flowcharts.
Maintenance Schedule Detail
Schedule Format:
Tabular format detailing tasks by mileage or time intervals (e.g., 1000km, 6000km, 12000km).
Heritage:
BMW Motorrad's lineage of horizontally opposed boxer engines, known for durability, reliability, and touring capabilities.
Airhead Era:
The R80, R90, and R100 series represent a significant evolution of the 'Airhead' platform, refined for performance and comfort.
Manufacturing Location:
Berlin-Spandau, Germany
Production Period For This Manual:
Specifically targets models produced around 1981, which include variations like R80/7, R80G/S, R100/7, R100S, R100RS, R100RT, R100CS.
