🏷️ Basic Information

Make:

BMW

Model:

R80, R90, R100

Model Variant:

Airhead Series

Year:

1979

Engine Code R80:

247

Engine Code R90:

248

Engine Code R100:

247

👋 Introduction

Positioning:

Essential resource for owners and mechanics of iconic BMW 'Airhead' motorcycles, crucial for maintaining classic performance and longevity.

Competitors:

Factory service manuals from BMW, Haynes, Clymer (often less detailed).

Features:

Detailed diagrams, step-by-step instructions, troubleshooting guides, comprehensive specifications.

Value:

Empowers owners to perform DIY maintenance and repairs, saving costs and preserving the value of their vintage BMWs.

📋 Manual Details

Primary Coverage:

Service, Repair, Workshop

Secondary Coverage:

Maintenance, Troubleshooting, Diagnostics, Overhaul

Estimated Page Count:

300-400 (estimated, actual may vary)

Type:

Service Repair Workshop Manual

Language:

English

Format:

Likely Printed, PDF version may be available

📖 Manual Coverage

Engine:

Complete overhaul, tuning, carburetor service (Bing), ignition system, lubrication system, cooling system (air-cooled).

Transmission:

5-speed gearbox overhaul, clutch service, drive shaft, final drive unit.

Chassis Suspension:

Front forks (BMW Telelever/Mono-lever variations may require supplemental data), rear swingarm, shock absorbers, steering head bearing.

Brakes:

Front disc brake system (including caliper rebuild, hydraulic lines), rear drum brake system.

Electrical System:

Wiring diagrams, alternator, starter motor, battery, lighting system, instrumentation.

Fuel System:

Fuel tank, fuel lines, petcock, carburetor tuning and rebuilding.

Bodywork Frame:

Frame inspection, body panel removal and installation, seat, fuel tank mounting.

Maintenance Procedures:

Regular servicing, oil changes, filter replacements, spark plug service, valve adjustments, carburetor synchronization.

Repair Procedures:

Engine rebuilds, transmission overhauls, brake caliper servicing, fork seal replacement, electrical component repair.

Troubleshooting:

Diagnostic flowcharts for common issues, ignition problems, fuel delivery issues, starting problems.

Torque Specifications:

Detailed torque values for all critical fasteners.

Depth:

Comprehensive: Covers everything from basic scheduled maintenance to full engine and transmission rebuilds, including detailed electrical system diagnostics.

📊 Manual Specifications

Digital Format:

PDF (commonly available for this era of manual)

Print Quality:

Original print quality (may vary with reproduction)

Binding Type:

Staple-bound or perfect bound (for printed versions)

Paper Type:

Standard paper (for printed versions)

⚙️ Engine Specifications

Engine Type:

Air-cooled, four-stroke, boxer-twin engine

Bore R80:

82 mm

Stroke R80:

74.5 mm

Displacement R80:

797.5 cc

Bore R90:

90 mm

Stroke R90:

70.6 mm

Displacement R90:

897.8 cc

Bore R100:

94 mm

Stroke R100:

70.6 mm

Displacement R100:

999.2 cc

Horsepower R80:

50 hp @ 6200 rpm (approx.)

Torque R80:

57 Nm @ 4800 rpm (approx.)

Horsepower R90:

65 hp @ 7000 rpm (approx.)

Torque R90:

70 Nm @ 5500 rpm (approx.)

Horsepower R100:

65 hp @ 7000 rpm (approx.)

Torque R100:

74 Nm @ 6000 rpm (approx.)

Carburetors:

Dual Bing carburetors (e.g., 32/36mm for R80, 40mm for R90/R100)

Fuel Type:

Unleaded gasoline (87 octane or higher recommended for modern fuels)

🔧 Transmission

Gearbox:

5-speed constant mesh, sequential manual

Clutch:

Single dry plate, diaphragm spring

Drive Type:

Shaft drive (universal joint and bevel gear final drive)

Gear Ratios:

Specific ratios detailed within the manual (vary by model/year)

Transmission Fluid Spec:

SAE 90 hypoid gear oil (or equivalent GL-4 spec)

📐 Dimensions

Wheelbase Approx:

1460-1500 mm (model dependent)

Dry Weight Approx:

200-230 kg (model dependent)

🛡️ Safety Features

Safety Standards:

Pre-modern motorcycle safety standards; manual focuses on mechanical integrity and safe operation.

Braking System:

Front hydraulic disc brake, rear drum brake.

Frame Construction:

Steel tube frame providing robust structural integrity.

💡 Technology Features

Infotainment System:

N/A (Analog instrumentation typical for the era)

Ignition System:

Breaker points ignition system (may have been upgraded to electronic ignition in some units).

🔧 Maintenance

Oil Change Interval:

Every 3,000-5,000 miles (approx., check manual for specific guidance)

Valve Adjustment Interval:

Every 6,000-10,000 miles (approx., check manual for specific guidance)

Spark Plug Replacement:

Every 6,000-12,000 miles (approx., check manual for specific guidance)

Engine Oil Spec:

SAE 20W-50 or SAE 10W-40 motorcycle-specific oil (check manual for temperature recommendations)

Brake Fluid Spec:

DOT 3 or DOT 4 hydraulic brake fluid

Final Drive Fluid Spec:

SAE 90 hypoid gear oil (GL-4)

Common Issues:

Carburetor synchronization drift, ignition coil failure, worn output shaft seal, clutch pushrod seal leaks, starter motor brushes, steering head bearing adjustment.

Preventative Maintenance:

Regular valve adjustments, proper carburetor tuning, keeping electrical connections clean, regular inspection of seals.

📚 Vehicle History

Heritage:

BMW Motorrad, a legacy of engineering excellence and innovation in motorcycle design since 1923.

Airhead Evolution:

The 'Airhead' boxer twin platform formed the backbone of BMW's motorcycle range for decades, evolving from the R50/5, R75/5 through to the later R100 models. The 1979 models represent a mature iteration of this design.

Production Era:

These models were produced through the 1970s and into the 1980s, with continuous updates.

🏆 Awards & Recognition

Industry Recognition:

Iconic status in the motorcycle community for reliability, touring capability, and unique engineering.

User Ratings:

Highly regarded by owners for their durability and rider comfort.