Positioning:
A critical resource for owners and restorers of classic BMW motorcycles from the /6 series, particularly the flagship R90S. Positions itself as the authoritative and indispensable guide for maintaining and repairing these iconic machines.
Alternatives:
While aftermarket manuals exist, this is presented as the 'COMPLETE official BMW /6 service manual,' implying superior accuracy, detail, and factory-specific procedures compared to Haynes or Clymer publications. The digital format also offers advantages over older, potentially outdated printed versions.
Features:
Hundreds of pages, hundreds of photos/illustrations, detailed substeps, notes/cautions/warnings, numbered instructions, bold figure numbers, enlarged insets, and comprehensive electrical troubleshooting with wiring diagrams.
Engine:
Detailed disassembly, assembly, tuning, troubleshooting, and repair of the boxer twin engine, including components like cylinders, pistons, crankshaft, camshaft, valves, timing, lubrication system, and cooling system (air-cooled).
Fuel System:
Carburetor (likely Bing) tuning, adjustment, overhaul, and troubleshooting; fuel tank, fuel lines, and fuel pump (if applicable).
Electrical System:
Comprehensive coverage including ignition system (points, coils, spark plugs), charging system (alternator, regulator), lighting, starter motor, battery, wiring harnesses, and detailed wiring diagrams for fault diagnosis and repair.
Drivetrain:
Clutch operation and adjustment, gearbox (transmission) disassembly, assembly, and repair, driveshaft, universal joints, and final drive (rear axle).
Chassis And Suspension:
Front fork (telescopic) overhaul, adjustment, and repair; rear shock absorber and swingarm inspection and service; wheel bearings and steering head bearings.
Brakes:
Front and rear brake system service, including caliper overhaul, pad replacement, master cylinder repair, brake fluid changes, and adjustment.
Bodywork And Frame:
Frame inspection, body panel removal and installation, seat, fenders, fuel tank mounting, and general cosmetic component service.
Routine Maintenance:
Oil changes, filter replacements, spark plug checks and replacement, valve adjustments, ignition timing checks, carburetor synchronization, chain adjustment (if applicable), brake fluid flush, and lubrication points.
Troubleshooting:
Systematic diagnostic procedures for common and uncommon problems across all vehicle systems, including engine performance issues, electrical faults, and braking system anomalies.
Repair And Rebuild:
Step-by-step instructions for complete disassembly and reassembly of major components, including engine internals, gearbox, forks, and brake systems.
Electrical Diagnostics:
Detailed guidance for diagnosing and repairing electrical issues, including the use of wiring diagrams, multimeter testing, and component-specific troubleshooting.
Depth:
Comprehensive, covering basic maintenance to full engine and transmission rebuilds. Suitable for both novice and experienced mechanics.
Compatibility:
Compatible with all PC-based Windows operating systems and Mac.
Printability:
All pages are printable, allowing for a physical copy or targeted printing of specific procedures.
Binding:
Digital (no physical binding, user prints as needed)
Paper Type Recommendation:
For optimal durability and readability when printed, consider using heavier weight paper (e.g., 20-24 lb bond) for procedures that require frequent reference or handling.
Type:
Air-cooled, four-stroke, boxer-twin cylinder
Displacement:
897.7 cc (for R90S)
Horsepower:
67 hp (DIN) @ 7,000 rpm (for R90S)
Torque:
77.4 Nm (57.1 lb-ft) @ 5,500 rpm (for R90S)
Carburetors:
2 x Bing 32/40/503-40 or 32/40/503-42 (for R90S)
System:
Battery-coil, dual ignition (dual spark plugs per cylinder for R90S)
Oil Change:
Typically every 3,000-5,000 miles (or annually), check manual for exact specification. Oil filter replacement often coincides with oil changes.
Valve Adjustment:
Generally recommended every 6,000-10,000 miles. Specific interval will be detailed in the manual.
Ignition Timing:
Check and adjust at major service intervals, typically coinciding with valve adjustments. Precise timing marks and procedures will be in the manual.
Engine Oil:
Typically SAE 20W-50 or SAE 20W-40, depending on climate. Manual will specify exact viscosity and API rating. Capacity approx. 2.5 liters.
Brake Fluid:
DOT 3 or DOT 4, depending on original specification. Manual will confirm.
Gearbox Oil:
Typically SAE 80W/90 API GL-5 hypoid gear oil. Capacity approx. 0.25 liters.
Final Drive Oil:
Typically SAE 80W/90 API GL-5 hypoid gear oil. Capacity approx. 0.20 liters.
Common Wear Items:
Cylinder head gaskets, clutch wear, steering head bearings, wheel bearings, fork seals, and ignition points/condensers are common wear items that may require attention over time.
Electrical Gremlins:
Aging wiring harnesses, faulty voltage regulators, and corrosion in connectors can lead to intermittent electrical issues. The manual's detailed diagrams are crucial for diagnosis.
Heritage:
BMW Motorrad boasts a long history of engineering excellence, particularly with its horizontally opposed 'boxer' engine motorcycles, known for durability, touring capability, and distinctive character.
Series Introduction:
The /6 series, introduced in 1973, represented a significant evolution for BMW's boxer twins, featuring updated styling, improved ergonomics, and enhanced performance. The R90S, launched in 1973, was the top-tier model, positioned as a sport-tourer with superior performance and styling.
R90S Production Years:
1973-1976
R60/6 Production Years:
1973-1976
R75/6 Production Years:
1973-1976
R90/6 Production Years:
1973-1976
Classic Status:
The R90S is widely recognized as a modern classic, celebrated for its performance, styling, and the era-defining engineering of BMW's boxer twins. Often featured in 'best bikes of the 70s' lists.
Owner Satisfaction:
High owner satisfaction, particularly among those who appreciate its build quality, touring comfort, and the unique riding experience provided by the boxer engine and shaft drive.
