Model:
R Series (R80, R90, R100)
Model Variant:
R80, R90, R100
Chassis Codes:
R80/7, R90/6, R100/7, R100S, R100RS, R100RT, R100GS, R100R (specific codes vary by submodel, this manual likely covers the most common 1991 variants)
Purpose:
Empowers owners and independent mechanics to perform all service and repair tasks, ensuring the longevity and optimal performance of their classic BMW airhead motorcycles.
Value Proposition:
Provides essential, detailed information that is crucial for maintaining these iconic motorcycles, often saving significant costs compared to dealership service. Essential for DIY enthusiasts.
Accessibility:
Digital format allows for easy access on computers, tablets, and smartphones, making it convenient for use in the workshop or on the go.
Accuracy:
Based on factory-approved procedures and specifications for the era.
Coverage:
Comprehensive service and repair for BMW R80, R90, and R100 series motorcycles manufactured around 1991. Includes engine, transmission, drivetrain, electrical system, chassis, suspension, brakes, and bodywork.
Pages:
Likely 300-500 pages, typical for a full service manual of this era.
Type:
Service and Repair Manual
Format:
Downloadable (Digital PDF)
Engine:
Twin-cylinder boxer engine (air-cooled), cylinder head overhaul, piston and ring replacement, valve timing and adjustment, oil pump, lubrication system, cooling system (air-cooled specific).
Transmission:
5-speed gearbox, clutch service (dry clutch for most models), gear shift mechanism, drive shaft, final drive unit (spline lubrication and seal replacement).
Electrical System:
Ignition system (CDI, points for earlier variants), charging system (alternator, voltage regulator), starter motor, battery, lighting system, wiring diagrams, instrument cluster, horn.
Chassis Suspension Brakes:
Frame inspection, front fork (telescopic, potentially Monolever for later R100 models), rear suspension (swingarm, twin shocks, potentially Monolever), wheel bearings, steering head bearings, front and rear brake systems (disc brakes, caliper overhaul, fluid replacement, bleeding).
Bodywork:
Fuel tank removal and installation, seat, fenders, side covers, instrument panel fairings (if applicable).
Maintenance:
Oil and filter changes, spark plug replacement, air filter service, valve clearance adjustment, brake pad replacement, brake fluid flush, drivetrain spline lubrication, general inspection.
Repair Overhaul:
Engine top-end overhaul, carburetor rebuild and synchronization, transmission disassembly and reassembly, fork seal replacement, brake caliper rebuilding, final drive overhaul.
Troubleshooting:
Diagnosing common running issues, electrical faults, starting problems, braking issues, and suspension noises. Includes symptom-based troubleshooting guides.
Depth:
Comprehensive. Covers routine maintenance to complete engine and transmission rebuilds. Detailed torque specifications, clearances, and procedures for specialized tasks.
Searchability:
Likely text-searchable, enabling quick access to specific topics.
Print Readability:
High quality digital reproduction, suitable for printing individual pages or the entire manual.
Binding:
Not applicable (Digital Download)
Paper:
Not applicable (Digital Download)
Type:
Air-cooled, horizontally opposed twin-cylinder (Boxer)
Displacement R80:
797.5 cc
Displacement R90:
897.9 cc
Displacement R100:
979.9 cc (approx. 1000cc)
Bore Stroke R80:
82 mm x 75 mm
Bore Stroke R90:
90 mm x 70.6 mm
Bore Stroke R100:
94 mm x 70.6 mm
Compression Ratio Typical:
8.2:1 to 9.5:1 (varies by model and year)
Power Output R80 Approx:
50 hp @ 6500 rpm
Power Output R90 Approx:
65 hp @ 7000 rpm
Power Output R100 Approx:
65 hp (R100/7, RS, RT) to 70 hp (R100GS, R) @ 7000-7250 rpm
Torque R80 Approx:
58 Nm @ 5500 rpm
Torque R90 Approx:
75 Nm @ 5500 rpm
Torque R100 Approx:
70-75 Nm @ 6000-6500 rpm
Carburetors:
Typically Dell'Orto VHB 26/28/30 or Bing 32/40/42 (specific to model and market)
Fuel Type:
Unleaded gasoline (91-95 RON recommended)
Fuel Capacity:
Approx. 18-23 liters (depending on tank size and model)
Certification:
Not applicable (motorcycle safety standards vary)
Braking System:
Dual disc front brakes (often 280-300mm), single disc rear brake (often 258-280mm). Brembo calipers common on later models. ABS was not standard on these models.
Suspension Stability:
Telescopic front forks, swingarm rear with twin shocks (or Monolever on R100GS/R) contribute to stability.
Frame Construction:
Robust tubular steel frame designed for stability and rider confidence.
Features:
Basic instrumentation: speedometer, tachometer, odometer, gear indicator (on some models), warning lights. No advanced infotainment systems.
Features:
None. These are classic motorcycles focused on mechanical purity.
Features:
None. Relies on purely mechanical and electrical systems.
Oil Change Engine:
Every 5,000 - 7,500 km (3,000 - 4,500 miles) or annually. Engine oil capacity typically around 2.0-2.5 liters.
Valve Adjustment:
Every 10,000 - 15,000 km (6,000 - 9,000 miles)
Final Drive Oil:
Every 10,000 - 15,000 km (6,000 - 9,000 miles). Capacity typically around 0.2 - 0.25 liters.
Brake Fluid Flush:
Every 2 years
Engine Oil:
SAE 20W-40 or 20W-50 motorcycle-specific oil, meeting API SE/SF specifications. Manual will specify exact grade and API rating.
Transmission Oil:
SAE 80W-90 hypoid gear oil
Final Drive Oil:
SAE 80W-90 hypoid gear oil
Brake Fluid:
DOT 3 or DOT 4 brake fluid (check manual for specific recommendation)
Common Wear Items:
Driveshaft splines (require regular greasing), output shaft seal, steering head bearings, wheel bearings, exhaust header gaskets, voltage regulator failure (on some models).
Carburetor Issues:
Diaphragm wear in Dell'Orto carbs, jetting issues, synchronization drift.
Electrical Issues:
Corrosion on connectors, aging wiring, regulator/rectifier failure, stator winding issues.
Legacy:
BMW's R series motorcycles, often referred to as 'airheads', represent a lineage of reliable, shaft-driven boxer twins that have been a cornerstone of the brand for decades.
Development:
The R80, R90, and R100 models represent a mature development of BMW's boxer engine platform, evolving from earlier designs with improvements in power, handling, and reliability.
Era:
These models were produced throughout the 1970s and 1980s, with 1991 representing the later iterations of these established designs. Production of R100 models ceased in the mid-1990s.
Manufacturing Location:
Berlin, Germany
