🏷️ Basic Information

Make:

BMW

Model:

R80 GS / R100 GS

Year:

1991

Product Type:

Service Repair Workshop Manual

👋 Introduction

Target Audience:

Owners of BMW R80 GS and R100 GS motorcycles, independent repair shops, and BMW motorcycle enthusiasts.

Manual Type Comparison:

This is a comprehensive workshop manual, far exceeding the scope of a basic owner's manual. It provides the technical depth required for genuine servicing and repairs.

Authenticity:

Represents information as used by professional mechanics, providing accurate and reliable repair data.

Accessibility:

Digital PDF format allows for easy storage, search, and viewing on multiple devices.

Comprehensiveness:

Covers virtually all aspects of maintenance, troubleshooting, and repair for the specified models.

📋 Manual Details

Primary Coverage:

BMW R80 GS and R100 GS Models

Specific Models Covered:

R80GS, R100GS

Model Year Coverage:

1991

Estimated Pages:

Over 300 pages (typical for comprehensive manuals of this era and type)

Type:

Workshop Manual / Service Manual / Repair Manual

Language:

English

Format:

PDF Download

📖 Manual Coverage

Engine:

Detailed inspection, disassembly, assembly, tuning, and repair procedures for the BMW boxer twin engines.

Fuel System:

Carburetor (Bing 32/40/35/40) overhaul, adjustment, troubleshooting, fuel pump, fuel lines, and fuel tank maintenance.

Ignition System:

Ignition timing, spark plugs, ignition coils, control unit troubleshooting and replacement.

Transmission:

Gearbox (5-speed) disassembly, assembly, clutch service, troubleshooting, and lubrication.

Drivetrain:

Final drive, driveshaft, universal joints, and rear wheel hub maintenance and repair.

Suspension:

Front forks (includingモノショック (Monolever) system), rear shock absorber, and swingarm maintenance, adjustments, and seal replacement.

Brakes:

Front and rear brake systems (disc brakes), master cylinders, brake calipers, brake lines, and fluid replacement.

Electrical System:

Wiring diagrams, battery maintenance, starter motor, alternator, lighting system, horn, and instrument cluster troubleshooting.

Frame And Bodywork:

Frame inspection, fairing removal/installation, seat, fuel tank, fenders, and luggage rack maintenance.

Wheels And Tires:

Spoke wheel maintenance, bearing replacement, tire mounting, and balancing.

Scheduled Maintenance:

Oil changes, filter replacements, spark plug checks, valve clearance adjustments, brake fluid flush, and general inspection schedules.

Troubleshooting:

Diagnostic flowcharts and symptom-based troubleshooting for common mechanical and electrical issues.

Engine Rebuild:

Complete procedures for engine disassembly, component inspection, machining recommendations, and reassembly.

Transmission Overhaul:

Step-by-step guide for gearbox disassembly, gear inspection, bearing replacement, and reassembly.

Carburetor Tuning:

Detailed instructions for synchronizing and adjusting Bing carburetors for optimal performance.

Electrical Diagnosis:

Guidance on testing electrical components, diagnosing shorts, open circuits, and charging system faults.

Suspension Adjustments:

Instructions for adjusting preload and damping on front and rear suspension units.

Brake System Service:

Procedures for bleeding brakes, replacing pads, and overhauling master cylinders and calipers.

Depth:

Comprehensive, covering basic maintenance to full engine and gearbox rebuilds, suitable for professional mechanics and experienced DIY enthusiasts.

Diagnostic Level:

Advanced diagnostic procedures and troubleshooting guides.

Specifications Detail:

Includes detailed torque specifications, clearances, and critical measurements for all components.

📊 Manual Specifications

Format:

PDF (Portable Document Format)

Searchability:

Likely text-searchable if digitally rendered from an original manual with OCR, allowing quick access to information.

Quality:

Dependent on the source scan. Professional scans aim for clear text and legible diagrams. Optimized for digital viewing and printing.

Binding:

N/A (Digital PDF format)

Paper Type:

N/A (Digital PDF format)

⚙️ Engine Specifications

Engine Type:

Air-cooled, four-stroke, horizontally opposed boxer twin-cylinder

Bore X Stroke R80:

80.0 mm x 78.0 mm (R80GS)

Bore X Stroke R100:

94.0 mm x 70.7 mm (R100GS)

Displacement R80:

797.5 cc (R80GS)

Displacement R100:

980 cc (R100GS)

Compression Ratio R80:

8.2:1 (R80GS)

Compression Ratio R100:

8.5:1 (R100GS)

Horsepower R80:

Approx. 50 HP @ 6500 RPM (R80GS)

Horsepower R100:

Approx. 60 HP @ 6500 RPM (R100GS)

Torque R80:

Approx. 57 Nm @ 5000 RPM (R80GS)

Torque R100:

Approx. 70 Nm @ 5000 RPM (R100GS)

Carburetor Type:

Dual Bing constant-velocity carburetors (e.g., 32mm for R80GS, 40mm for R100GS)

Fuel Type:

Unleaded Gasoline, minimum 91 RON (Regular)

Fuel Capacity:

26 Liters (including 5-liter reserve)

🔧 Transmission

Type:

5-speed manual gearbox with constant mesh gears

Clutch:

Single dry plate, hydraulically actuated diaphragm spring clutch

Drive Type:

Shaft drive to rear wheel

Transmission Fluid Spec:

API GL-5, SAE 75W/90 Gear Oil (or specified BMW equivalent)

📐 Dimensions

Length Approx:

2220 mm

Width Approx:

930 mm

Height Approx:

1290 mm

Dry Weight R80:

Approx. 195 kg (R80GS)

Dry Weight R100:

Approx. 200 kg (R100GS)

Gross Weight R100:

Approx. 390 kg (R100GS)

🛡️ Safety Features

Crash Test Data:

N/A (Motorcycle, typically not subject to same ratings as cars)

Braking System:

Dual front disc brakes with 4-piston calipers, single rear disc brake. Often equipped with BMW's EVO brake system on later models, but 1991 likely uses standard Brembo.

Suspension Stability:

Monolever rear suspension for reduced drivetrain reaction and improved stability.

Frame Construction:

Tubular steel frame designed for robust off-road and touring use.

💡 Technology Features

Features:

N/A (No electronic infotainment systems typical for this era)

Features:

N/A (No electronic driver assistance features)

Features:

N/A

🔧 Maintenance

Oil Change Interval:

Every 5,000 - 10,000 km (depending on riding conditions), or annually. Manual will specify precise intervals.

Filter Change Interval:

Oil filter: Typically with every oil change. Air filter: Every 10,000 - 20,000 km.

Valve Clearance Interval:

Every 10,000 km

Spark Plug Service:

Check/replace every 10,000 km

Brake Fluid Flush:

Every 2 years

Engine Oil Spec:

Viscosity: SAE 20W-50 or SAE 15W-40. Type: API SG or higher. Capacity: Approx. 2.5 Liters (with filter).

Brake Fluid Spec:

DOT 4

Transmission Fluid Spec:

API GL-5, SAE 75W/90 Gear Oil

Fork Oil Spec:

Specific weight and quantity will be detailed in the manual (typically around SAE 10W).

Oil Leaks:

Common on older boxer twins, particularly around the cylinder base gaskets and pushrod tubes.

Starter Clutch Wear:

Can wear over time, leading to intermittent starter engagement.

Clutch Slave Cylinder Leaks:

Hydraulic slave cylinder for the clutch can develop leaks.

Carburetor Synchronization:

Bing carburetors require regular synchronization for smooth running.

Electrical Connections:

Corrosion or loose connections can cause intermittent electrical faults.

📚 Vehicle History

Bmw Motorrad:

BMW Motorrad has a long and storied history dating back to the early 20th century, renowned for engineering excellence, reliability, and innovation in motorcycle design.

Gs Lineage:

The 'GS' (Gelände/Straße - Off-road/Street) designation signifies BMW's highly successful dual-sport motorcycle lineage. The R80GS and R100GS were revolutionary in their time, creating the adventure touring segment.

Predecessors:

Evolved from BMW's traditional R-series boxer platform, incorporating lessons learned from rally racing and off-road expeditions.

Key Innovations Of Gs:

Introduction of the Monolever single-sided swingarm and Paralever (on later models), robust suspension, and powerful boxer engines made them ideal for long-distance adventure riding.

Production Period R80Gs:

1987–1990

Production Period R100Gs:

1987–1996

Production Period R100Gs Pd:

1988-1990 (Paris-Dakar edition)

Manufacturing Location:

Berlin, Germany (BMW Motorrad plant)

🏆 Awards & Recognition

Segment Creation:

Widely recognized as the motorcycle that defined the adventure touring market, earning numerous accolades for its capability and ruggedness.

Expert Reviews:

Consistently praised by motorcycle publications and riders for its reliability, comfort on long distances, and off-road prowess.

Manufacturer Standards:

Built to BMW's stringent quality and engineering standards.