🏷️ Basic Information

Make:

BMW

Model:

R90

Year:

1990

Vehicle Code:

R90/6, R90S (though the manual is likely for the R90/6 as the S was an earlier variant)

👋 Introduction

Market Segment:

Premium touring/sport motorcycle of its era, known for its air-cooled boxer twin engine and shaft drive.

Key Competitors:

Honda GL series, Yamaha XS series, Kawasaki Z series, Moto Guzzi T and V series.

Unique Selling Points:

BMW's renowned reliability, shaft drive for low maintenance, distinctive boxer engine layout, and comfortable touring ergonomics.

Primary Users:

BMW R90 owners seeking to perform maintenance and repairs themselves, enthusiasts, and independent repair shops.

📋 Manual Details

Coverage Scope:

All service and repair procedures for the 1990 BMW R90 motorcycle

Page Count:

Estimated 300-500 pages (typical for comprehensive service manuals of this era)

Manual Type:

Service and Repair Manual

Language:

English

Format:

Digital Download (PDF)

📖 Manual Coverage

Engine Service:

Complete engine overhaul, tuning, component inspection, and replacement procedures for the R90 Boxer engine.

Fuel System:

Carburetor (likely Dell'Orto PHM 40) overhaul, adjustment, fuel pump, fuel lines, and fuel tank servicing.

Ignition System:

Ignition timing, spark plugs, ignition coils, breaker points (if applicable for the specific 1990 model year variant, though electronic ignition was common), and associated wiring.

Transmission And Drivetrain:

Gearbox disassembly, assembly, maintenance, clutch operation, shaft drive system service, and final drive lubrication.

Brake System:

Front and rear brake system servicing, fluid replacement, caliper maintenance, master cylinder overhaul, and disc/pad inspection.

Suspension And Steering:

Front fork (likely telescopic with air assistance or conventional damping) overhaul, rear shock absorber service, swingarm maintenance, and steering head bearing adjustment.

Electrical System:

Wiring diagrams, battery maintenance, charging system (alternator, voltage regulator), lighting system, starter motor, and instrument cluster.

Chassis And Bodywork:

Frame inspection, body panel removal and installation, seat servicing, and exhaust system maintenance.

Routine Maintenance:

Oil changes, filter replacement, spark plug checks, chain adjustment (if applicable, though shaft drive is more common), tire pressure checks, and general inspection procedures.

Troubleshooting Diagnostics:

Step-by-step diagnostic procedures for common starting, running, and electrical issues, with symptom-based fault finding.

Component Overhaul:

Detailed instructions for the complete disassembly, cleaning, inspection, repair, and reassembly of all major motorcycle components.

Recalibration And Adjustment:

Specific procedures for carburetor synchronization, ignition timing adjustments, valve clearance settings, and brake lever/pedal free play.

Specifications And Tolerances:

Precise technical specifications, torque values, clearances, and wear limits for all serviceable parts.

Depth Of Coverage:

Comprehensive, covering everything from basic owner maintenance to full engine rebuilds and complex electrical diagnostics.

📊 Manual Specifications

File Format:

PDF

Searchability:

Likely text-searchable PDF allowing quick access to specific topics.

Print Quality:

High-resolution scans of original manual pages, suitable for digital viewing and printing.

Binding Type:

N/A (Digital Download)

Paper Type:

N/A (Digital Download)

⚙️ Engine Specifications

Engine Type:

Air-cooled, four-stroke, horizontally opposed twin-cylinder (Boxer)

Displacement:

897 cc (54.7 cu in)

Bore X Stroke:

90 mm x 70.6 mm

Compression Ratio:

9.5:1 (typical, may vary slightly)

Horsepower:

60 hp (45 kW) @ 6,200 rpm (R90/6)

Torque:

75 Nm (55 lb-ft) @ 4,500 rpm (R90/6)

Fuel Delivery:

Two Dell'Orto PHM 40 CD carburetors

Fuel Type:

Unleaded gasoline (Premium, 91 octane or higher)

Oil Capacity:

Approx. 2.5 liters (2.6 US qt)

Oil Type:

SAE 20W-50 motorcycle-specific oil (e.g., Castrol GTX or equivalent)

Cooling Method:

Air-cooled

🔧 Transmission

Transmission Type:

5-speed constant mesh gearbox

Optional Features:

N/A (5-speed was standard)

Clutch:

Single dry plate, diaphragm spring clutch

Final Drive:

Enclosed shaft drive

Gearbox Oil Type:

API GL-4 SAE 90 hypoid gear oil (e.g., Castrol EPX 90 or equivalent)

📐 Dimensions

Length:

Approx. 2,180 mm (85.8 in)

Width:

Approx. 750 mm (29.5 in) (handlebars)

Height:

Approx. 1,180 mm (46.5 in) (seat height)

Dry Weight:

Approx. 200 kg (441 lbs)

Wet Weight:

Approx. 215 kg (474 lbs)

Gross Vehicle Weight Rating:

Approx. 400 kg (882 lbs)

Front Tire Size:

3.50-18 4PR

Rear Tire Size:

4.00-18 4PR

Front Wheel Type:

Spoked, 18-inch diameter

Rear Wheel Type:

Spoked, 18-inch diameter

🛡️ Safety Features

Safety Standards:

Compliant with relevant automotive safety standards for motorcycles of the era.

Braking System:

Dual disc front brakes (often 280mm), single disc rear brake (often 240mm) with twin-piston calipers. ABS was not standard.

Lighting:

Halogen headlamp, tail light, brake light, and turn signals.

💡 Technology Features

Infotainment System:

N/A (Analog instruments: speedometer, tachometer, voltmeter, oil pressure light, neutral indicator, turn signal indicators, high beam indicator).

Assistance Features:

N/A (No electronic rider aids like ABS or traction control were standard).

🔧 Maintenance

Oil Change Interval:

Every 3,000 - 5,000 km (1,800 - 3,000 miles) or annually, whichever comes first.

Valve Adjustment Interval:

Every 6,000 - 10,000 km (3,700 - 6,200 miles).

Spark Plug Replacement:

Every 10,000 - 15,000 km (6,200 - 9,300 miles).

Brake Fluid Flush:

Every 2 years or as recommended by the manufacturer.

Final Drive Oil Change:

Every 10,000 - 12,000 km (6,200 - 7,500 miles).

Brake Fluid Type:

DOT 4 (or DOT 3, check specific model variation)

Final Drive Oil Capacity:

Approx. 150 ml (0.16 US qt)

Common Wear Items:

Camshaft and tappets (wear), output shaft seal leaks, clutch wear, electrical connector corrosion, and front fork seal leaks.

Carburetor Issues:

Difficulty synchronizing, worn jets or floats, leading to poor idle or performance.

📚 Vehicle History

Manufacturer History:

BMW Motorrad has a long history of producing reliable, technologically advanced motorcycles since the early 20th century, known for boxer engines and shaft drive.

R Series Heritage:

The R90 is part of BMW's iconic R series, which began with the R32 in 1923. The R90 lineage traces back through models like the R75/5 and R60/7, culminating in the R100 series.

R90 Specific Development:

The R90 was introduced in 1973 as a more powerful successor to the R75/5, with the R90/6 offering a balance of performance and touring comfort, while the R90S was the sportier, faired variant.

Production Years:

The R90 series (including R90/6 and R90S) was produced from 1973 to 1976. A 1990 reference likely indicates a manual for a later model or a vintage enthusiast market; typically R90s are 1970s models. This manual might cover general Boxer principles applicable to later models or is a misprint year for the R90 model itself.

🏆 Awards & Recognition

Motorcycle Reviews:

The R90/6 and R90S were generally well-received for their performance, build quality, and distinctive character, becoming sought-after classics.

Reliability Reputation:

High, known for longevity and durability when properly maintained, characteristic of BMW motorcycles.