Model:
R Series (R80, R90, R100)
Chassis Codes:
R80/7, R90/6, R100/7, R100S, R100RT, R100RS
Target Audience:
BMW motorcycle owners, independent repair shops, and vintage motorcycle enthusiasts seeking detailed maintenance and repair guidance.
Manual Value Proposition:
Provides essential technical data for maintaining and repairing the iconic BMW R80, R90, and R100 airhead motorcycles, empowering owners to perform work themselves and ensure longevity.
Comprehensiveness:
Covers the full spectrum of service, repair, and troubleshooting for the specified models.
Historical Significance:
Essential for preserving and maintaining some of BMW's most celebrated and enduring motorcycle designs.
Engine:
Full Engine Overhaul, Tuning, Carburetor Adjustment, Ignition System, Lubrication System, Cooling System (Air-cooled)
Transmission:
Gearbox Disassembly and Reassembly, Clutch Adjustment and Replacement, Driveshaft and Final Drive Maintenance
Chassis And Suspension:
Front Fork Overhaul and Adjustment, Rear Shock Absorber Service, Wheel Bearing Replacement, Swingarm Bushing Service
Brakes:
Front and Rear Brake System Service (Drum and Disc), Hydraulic System Bleeding and Maintenance
Electrical System:
Wiring Diagrams, Charging System (Alternator, Regulator), Starting System, Lighting System, Ignition System Components
Fuel System:
Fuel Tank Service, Fuel Lines, Fuel Pump (if applicable), Carburetor Disassembly and Reassembly (e.g., Bing 32/40/42)
Routine Maintenance:
Oil Changes, Filter Replacements, Spark Plug Service, Valve Adjustment, Brake Pad/Shoe Inspection, Tire Pressure Checks
Troubleshooting:
Diagnostic Flowcharts, Common Problems and Solutions, Identifying Faults
Repair And Rebuild:
Component Disassembly, Component Reassembly, Parts Replacement Procedures, Engine Rebuild Steps
Special Tools:
Identification and Usage of BMW-specific tools required for maintenance and repair
Diagnostic Capability:
Comprehensive diagnostic procedures for all major systems, including electrical troubleshooting via wiring diagrams.
Rebuild Instructions:
Detailed, step-by-step instructions for complete engine, transmission, and suspension overhauls.
Specification Accuracy:
Includes precise torque values, clearances, fluid capacities, and electrical resistance readings.
Searchability:
Likely text-searchable PDF for quick information retrieval.
Image Resolution:
High-resolution images and diagrams suitable for printing.
Physical Format Note:
As a digital download, binding type is not applicable. If printed, typically a comb or spiral binding for lay-flat use.
Physical Format Note:
As a digital download, paper type is not applicable. If printed, historically service manuals used durable, matte paper.
Engine Type:
Air-cooled, four-stroke, boxer twin-cylinder engine
Displacement R80:
797.5 cc
Displacement R90:
897.9 cc
Displacement R100:
979.5 cc
Power Output R80 Approx:
50 hp @ 6500 rpm
Power Output R90 Approx:
60 hp @ 6500 rpm
Power Output R100 Approx:
65-70 hp @ 7000 rpm (varies by model variant)
Torque R100 Approx:
75 Nm @ 5000 rpm
Carburetor Type:
Dual Bing constant velocity carburetors (e.g., Bing 32/40/42 depending on model)
Fuel Type:
Unleaded gasoline (91 RON or higher)
Fuel Delivery:
Gravity feed from fuel tank, some models may have electric fuel pump assistance.
Gearbox Type:
5-speed constant mesh manual transmission
Transmission Variants:
All R-series models for 1981 typically featured the 5-speed gearbox; no common automatic or alternative transmissions.
Clutch Type:
Single dry plate clutch, operated by cable.
Final Drive:
Shaft drive to rear wheel.
Wheelbase Approx:
1460 mm - 1480 mm (varies by model)
Seat Height Approx:
780 mm - 800 mm (varies by model)
Dry Weight Approx:
200 kg - 220 kg (varies by model)
Fuel Tank Capacity Approx:
20 liters (including reserve)
Safety Classification Note:
No formal crash safety ratings as applied to modern vehicles. Focus is on rider safety through design and maintenance.
Braking System:
Combination of disc brakes (front) and drum or disc brakes (rear) depending on model variant. Effective hydraulic actuation.
Suspension Stability:
Well-engineered telescopic front forks and dual rear shock absorbers providing stable handling.
Frame Construction:
Robust steel tube frame providing a strong and rigid chassis.
Lighting:
Comprehensive headlight, taillight, and indicator system for visibility.
Infotainment System:
None (pre-digital era). Focus is on mechanical and electrical systems.
Driver Assistance Features:
None. The technology is purely mechanical and electrical systems control.
Connectivity Options:
None. No electronic connectivity features.
Oil Change Interval:
Every 5,000 - 10,000 km (3,000 - 6,000 miles) or annually, whichever comes first (refer to manual for specific recommendations).
Valve Adjustment Interval:
Every 10,000 km (6,000 miles).
Spark Plug Replacement:
Every 10,000 - 20,000 km (6,000 - 12,000 miles).
Engine Oil Type:
API SF or SG classification, SAE 20W-50 or 10W-40 (refer to manual for temperature specific recommendations).
Engine Oil Capacity:
Approximately 2.0 - 2.5 liters (including filter).
Transmission Oil Type:
Hypoid gear oil, API GL-5, SAE 80W-90.
Final Drive Oil Type:
Hypoid gear oil, API GL-5, SAE 80W-90.
Brake Fluid Type:
DOT 3 or DOT 4 hydraulic brake fluid.
Clutch Wear:
The clutch can wear over time, especially with aggressive riding, leading to slipping. Regular adjustment and eventual replacement are necessary.
Ignition Points And Condenser:
Mechanical ignition points require periodic cleaning and adjustment for optimal performance. Condenser failure can cause starting issues.
Oil Leaks:
Aging seals and gaskets can lead to minor oil leaks, particularly around the pushrod tubes and cylinder bases. Regular inspection and gasket replacement are recommended.
Carburetor Tuning:
Bing carburetors can require precise tuning and cleaning to maintain smooth running and optimal fuel efficiency.
Bmw Motorcycle Legacy:
BMW has a long-standing reputation for building durable, reliable, and technologically advanced motorcycles since the early 20th century.
R Series Airhead Development:
The R-series boxer twins evolved from the post-war R24 and were a staple of BMW's motorcycle lineup for decades, known for their longevity and shaft drive. The R80, R90, and R100 represent the larger displacement, more powerful iterations of this lineage.
1981 Model Year Significance:
The 1981 models represent a mature stage in the development of the R-series, incorporating refinements and updates from earlier versions, including the R100RT becoming a highly successful touring model.
Manufacturing Location:
Munich, West Germany
Model Recognition:
The R-series airheads are widely recognized for their durability, reliability, and timeless design, earning them a strong following among enthusiasts and a reputation as 'modern classics'.
Owner Satisfaction:
Consistently high owner satisfaction due to the robust engineering and capability for long-term ownership with proper maintenance.
Manual Certification Note:
No formal certifications for manuals, but its value is derived from its accuracy and completeness for the specific BMW models.
