🏷️ Basic Information

Make:

BMW

Model:

R80 GS / R100 GS

Year:

1981

Engine Code Primary:

Type 247 (Boxer Twin)

Gs Model Designation:

First generation of BMW's 'Gelande/Strasse' (Off-road/Street) dual-purpose motorcycles

Chassis Type:

Paralever (introduced later, but manual likely covers precursor frame designs and early single-sided swingarm)

👋 Introduction

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.

Market Competitors Era:

Honda Transalp, Yamaha XT600, Kawasaki KLR600, Suzuki DR600, Moto Guzzi V50/V75 (less direct competitors)

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

Primary Coverage:

Comprehensive service and repair for BMW R80 GS and R100 GS models

Secondary Coverage:

Maintenance, troubleshooting, diagnostics, and general overhaul

Estimated Pages:

300-500 (typical for comprehensive workshop manuals of this era)

Type:

Workshop Manual / Service Manual / Repair Manual

Language:

English

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

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.

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.

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

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)

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

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

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)

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

Wheelbase Approx:

1440 mm - 1460 mm (56.7 - 57.5 inches)

Seat Height Approx:

860 mm - 910 mm (33.9 - 35.8 inches)

Dry Weight Approx R80:

190-200 kg (419-441 lbs)

Dry Weight Approx R100:

200-210 kg (441-463 lbs)

Gross Vehicle Weight Rating Gvwr Approx:

380-400 kg (838-882 lbs)

🛡️ Safety Features

Crash Test Results:

N/A (Motorcycle safety ratings are not standardized like automobiles)

Braking System:

Hydraulic disc brakes (front and rear), dual-piston calipers typical.

Lighting:

Halogen headlamp, integrated turn signals and taillight.

Frame Design:

Steel tube frame designed for strength and load-carrying capacity.

Engine Guard Options:

Aftermarket or factory-optional engine crash bars were common for this model.

💡 Technology Features

Infotainment System:

N/A (Basic motorcycle design of the era)

Rider Aids:

None (This era of motorcycle predates electronic rider aids like ABS or traction control).

Connectivity Features:

None

🔧 Maintenance

Oil Change Interval:

Typically every 5,000 - 7,500 km (3,000 - 5,000 miles) or annually. Check manual for exact figure.

Valve Adjustment Interval:

Every 10,000 - 15,000 km (6,000 - 9,000 miles). Requires specialized knowledge of BMW boxer valve adjustment.

Spark Plug Replacement:

Check/clean at 5,000 km, replace at 10,000-20,000 km depending on type.

Final Drive Oil Change:

Every 10,000 - 20,000 km (6,000 - 12,000 miles).

Engine Oil Type:

Multi-viscosity oil, e.g., SAE 20W-50 or SAE 15W-50, meeting API SF or SG specifications. (Manual will specify exact BMW approval or equivalent).

Engine Oil Capacity:

Approximately 2.0 - 2.2 liters (2.1 - 2.3 US quarts) with filter change. Manual is definitive.

Brake Fluid Type:

DOT 4 brake fluid (ensure compatibility with seals, manual will confirm).

Common Wear Items:

Fork seals, clutch plates, swingarm bearings, starter motor brushes, cam follower wear.

Electrical Gremlins:

Loose connections, corroded grounds, failing voltage regulators can be common with age and mileage.

Fuel System Maintenance:

Carburetor synchronization and cleaning, checking fuel petcock and lines for leaks or blockages.

Final Drive Leaks:

Potential for oil seal leaks around the driveshaft boot or wheel hub.

📚 Vehicle History

Bmw Motorcycle Legacy:

BMW has a long and storied history in motorcycle production, dating back to 1923. Known for engineering excellence, reliability, and shaft drive technology.

R80Gs R100Gs Genesis:

The R80 G/S (and subsequent R100 G/S) was BMW's groundbreaking entry into the dual-sport market, leveraging their established boxer twin platform with updated suspension and chassis components for off-road capability.

Key Milestones 1980S:

The R80 G/S was introduced in 1980, followed by the R100 G/S in 1987, and the introduction of the Monolever rear suspension further refined the model. The 1981 model year represents an early iteration of this influential design.

Production Period:

R80 G/S: 1980-1987; R100 GS: 1987-1996 (The 1981 models are early R80 G/S variants.)

Manufacturing Location:

Berlin, Germany (Spandau factory)

🏆 Awards & Recognition

Market Impact:

The R80 G/S and its successors are widely considered pioneers of the modern adventure touring motorcycle segment, influencing countless designs.

Enthusiast Recognition:

Highly regarded by owners and the motorcycle press for their durability, capability, and classic styling. Often the subject of extensive modifications and restorations.