Segment:
Classic BMW Airhead Motorcycle segment
Competitors:
Manuals for other contemporary large-displacement motorcycles, but specifically targeting BMW R series enthusiasts.
Manual Value:
Authoritative guide for preserving and restoring a classic BMW motorcycle.
Content Emphasis:
Focus on detailed procedures, diagnostic information, and technical specifications crucial for accurate repairs and maintenance.
Primary Coverage:
Full Service, Repair, Maintenance, Rebuild, Refurbishment, Restoration
Estimated Page Count:
Likely over 400 pages (typical for comprehensive BMW motorcycle service manuals)
Type:
Full Service and Repair Manual
Format:
Likely Digital (PDF) given description, potentially printable
Searchability:
Searchable text for quick information retrieval (typical for high-quality digital manuals).
Printability:
Printable pages for workshop use.
Engine Mechanical:
Engine overhaul, cylinder head repair, piston replacement, valve adjustment, crankshaft and connecting rod inspection, timing chain/belt maintenance.
Fuel System:
Carburetor tuning and rebuilding (e.g., Bing carburetors), fuel pump inspection and repair, fuel tank and lines maintenance.
Ignition System:
Ignition timing adjustment, spark plug inspection, coil and ignition module testing, breaker point (if applicable) maintenance.
Transmission Drivetrain:
Gearbox disassembly and reassembly, clutch adjustment and replacement, driveshaft and final drive inspection and servicing.
Electrical System:
Wiring diagrams, alternator and starter motor testing, battery maintenance, lighting system troubleshooting, horn and switchgear servicing.
Braking System:
Brake fluid replacement, caliper and master cylinder servicing, brake pad and disc inspection and replacement, brake line maintenance.
Suspension Steering:
Front fork overhaul, rear shock absorber servicing, steering head bearing adjustment, wheel bearing replacement.
Frame Bodywork:
Frame inspection, fairing and body panel repair, seat upholstery, exhaust system maintenance.
Routine Maintenance:
Oil changes, filter replacements, lubrication points, chain adjustment, tire pressure checks, brake adjustments.
Diagnostic Troubleshooting:
Step-by-step diagnostic procedures for common and uncommon issues, fault finding guides.
Rebuild Procedures:
Detailed instructions for complete engine, gearbox, and suspension rebuilds.
Special Tools:
Identification and usage of specialized tools required for specific repair procedures.
Electrical Troubleshooting:
Detailed wiring diagrams, component testing procedures, and common electrical fault diagnosis.
Engine Diagnostics:
Compression testing, ignition timing checks, fuel mixture adjustments, and identification of mechanical issues.
Depth:
Comprehensive, covering basic maintenance to complete engine rebuilds and advanced diagnostics.
Engine Type:
Air-cooled, four-stroke, horizontally opposed twin-cylinder (Boxer)
Displacement:
898 cc (for R90/6 designation)
Bore X Stroke:
90 mm x 70.6 mm
Compression Ratio:
Approximately 9.5:1
Valve Train:
Overhead valves (OHV), pushrod actuated
Horsepower:
Approx. 60 hp at 6,500 rpm (R90/6)
Torque:
Approx. 70 Nm (52 lb-ft) at 5,000 rpm (R90/6)
Carburetion:
Dual Bing 32/40mm carburetors (common on R90/6)
Fuel Type:
Unleaded gasoline (premium recommended)
Oil Capacity:
Approx. 2.5 Liters (5.3 US Pints)
Oil Filter Type:
Internal oil screen and potentially a spin-on filter depending on exact variant/aftermarket fitment. Manual will specify.
Engine Variant:
R90/6 (typically the standard model)
Type:
5-speed, constant mesh, sequential manual transmission
Clutch Type:
Single dry plate, diaphragm spring
Gear Ratios:
Specific ratios will be detailed in the manual; typically geared for touring.
Fluid Type:
GL-1 or GL-4 Hypoid Gear Oil (e.g., SAE 80W/90), manual will specify exact BMW recommendation.
Wheelbase:
Approx. 1465 mm (57.7 inches)
Length:
Approx. 2180 mm (85.8 inches)
Seat Height:
Approximately 820 mm (32.3 inches)
Dry Weight:
Approx. 205 kg (452 lbs)
Fuel Tank Capacity:
Approx. 19 Liters (5.0 US Gallons), including reserve
Crash Test Data:
N/A for motorcycles of this era in the context of automotive crash testing.
Braking System Type:
Dual front disc brakes, single rear disc brake (typical for R90/6)
Lighting:
Halogen headlight, taillight, brake light, turn signals.
Oil Change Interval:
Typically every 5,000-7,500 km (3,000-4,500 miles) or annually. Manual will provide exact interval.
Valve Adjustment Interval:
Typically every 10,000-15,000 km (6,000-9,000 miles). Manual will provide exact interval.
Gearbox Final Drive Oil Change:
Typically every 10,000-20,000 km (6,000-12,000 miles). Manual will provide exact interval.
Engine Oil:
Typically SAE 20W/50 or SAE 15W/40 motorcycle-specific oil. Manual will specify exact BMW recommendation.
Brake Fluid:
DOT 3 or DOT 4 brake fluid (manual will specify).
Final Drive Oil:
SAE 80W/90 hypoid gear oil (API GL-5 or GL-6 recommended by some, but manual will specify BMW's preference, often GL-1 or GL-4).
Common Wear Items:
Clutch wear, output shaft seal leaks, fork seal leaks, charging system (rectifier/regulator) issues, carburetor synchronization drift.
Routine Checks:
Regular checking of electrical connections, spark plugs, and fluid levels is crucial for longevity.
Bmw Motorcycle Legacy:
BMW has a long and distinguished history in motorcycle manufacturing, known for engineering excellence, durability, and shaft drive systems.
Airhead Series:
The R90 is part of the iconic 'Airhead' series, characterized by their air-cooled boxer engines, which were produced for decades. It represented a significant step up in performance and touring capability from earlier models.
Production Period:
The R90/6 model was produced from 1973 to 1976. A '1987' listing might indicate a later model or a reference to a manual that covers a broader range or is a reprint.
Industry Reputation:
The R90 series (particularly the R90/6 and R90S) is highly regarded for its blend of performance, comfort, and build quality, earning a reputation as a premier touring motorcycle of its time.
Contemporary Reviews:
Critically acclaimed in its day for its smooth power delivery, sophisticated chassis, and excellent build quality compared to many competitors.
