🏷️ Basic Information Identification Make: BMW Model: R90 Model Variant: R90/6 Generation Model Years Covered: 1973-1976 Codes Chassis Codes: R90/6 👋 Introduction Market Position Market Niche: Premium large-displacement touring and sport-touring motorcycle segment Competitive Analysis Key Competitors: Honda CB750, Kawasaki Z1, Moto Guzzi V7 series, Ducati 750 GT Key Features Defining Characteristics: Shaft drive, boxer twin engine, robust build quality, touring comfort, reliable performance Target Audience: Touring riders, sport-touring enthusiasts, enthusiasts seeking reliable and capable classic motorcycles 📋 Manual Details Coverage Areas General Coverage: Comprehensive service and repair for BMW R90/6 motorcycles Page Count Estimated Page Count: ~300-500 (typical for WSM of this era) Manual Type Manual Type: Workshop Service Manual (WSM) Language Language: English Format Format: Print or Digital (PDF) 📖 Manual Coverage Systems Covered Engine Systems: Engine overhaul, cylinder head, piston, crankshaft, camshaft, valve train, lubrication, cooling (air-cooled), ignition system, fuel system (carburetors) Drivetrain Systems: Clutch, transmission (gearbox), driveshaft, final drive (bevel gear) Chassis Systems: Frame, suspension (front forks, rear shocks), steering, brakes (front and rear), wheels, tires Electrical Systems: Wiring diagrams, battery, charging system (alternator, regulator), lighting, ignition, instrumentation Bodywork And Fittings: Fuel tank, seat, fenders, exhaust system, controls, body panels Procedures Included Maintenance Procedures: Routine checks, lubrication, filter replacement, spark plug service, brake adjustments, carburetor synchronization, valve clearance adjustment Repair Procedures: Engine rebuild, transmission overhaul, suspension repair, brake caliper service, electrical component replacement Troubleshooting Guides: Diagnosis of common problems, fault finding charts, diagnostic procedures Special Tools And Jigs: Identification and usage of BMW-specific tools for repair and maintenance Technical Depth Depth Of Coverage: Detailed step-by-step instructions, torque specifications, clearances, technical data, diagrams, and exploded views 📊 Manual Specifications File Format Digital Format: PDF (searchable text often present in higher quality scans) Print Quality Print Quality Description: Clear text and legible diagrams (dependent on original source and scan quality) Binding Type Binding Type: Spiral-bound or Perfect-bound (for printed versions) Paper Type Paper Type: Matte or semi-gloss paper (for printed versions) ⚙️ Engine Specifications Primary Engine 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 (3.54 in x 2.78 in) Compression Ratio: 9.5:1 Performance Horsepower: 67 hp (50 kW) @ 6,500 rpm (approx.) Torque: 77 Nm (57 lb-ft) @ 5,000 rpm (approx.) Fuel System Carburetors: 2 x Bing 32/40mm constant-velocity carburetors Fuel Type: Unleaded gasoline (91 octane or higher recommended) Lubrication Oil Capacity: 2.5 Liters (2.6 US qt) Oil Type: SAE 20W-50 or 10W-40 motorcycle specific 🔧 Transmission Standard Transmission Type: 5-speed manual, constant mesh Features Drive Type: Shaft drive Final Drive Ratio: 1:3.38 (9/31 teeth) Transmission Oil Capacity: 0.25 Liters (0.26 US qt) Transmission Oil Type: Gear oil, SAE 90 (API GL-4) 📐 Dimensions Exterior Length: 2180 mm (85.8 in) Width: 800 mm (31.5 in) (at handlebars) Height: 1150 mm (45.3 in) (at handlebars) Weights Dry Weight: 210 kg (463 lbs) Wet Weight: 226 kg (498 lbs) Fuel Capacity: 17 Liters (4.5 US gal), including 3 Liters reserve Seat Height: 820 mm (32.3 in) 🛡️ Safety Features Ratings Safety Rating Context: Motorcycles of this era were not subject to standardized crash test ratings like modern cars. Active Features Braking System: Front: Dual 260mm discs with dual-piston calipers; Rear: 260mm drum brake Lighting System: Halogen headlight, taillight, brake light, turn signals Passive Features Frame Construction: Steel duplex cradle frame Wheel Type: Wire-spoked wheels, tubed tires 💡 Technology Features Infotainment Infotainment Features: N/A (Classic motorcycle, no modern infotainment systems) Driver Assistance Driver Assistance Systems: N/A (Classic motorcycle, no electronic rider aids) Connectivity Connectivity Options: N/A (Classic motorcycle, no electronic connectivity) 🔧 Maintenance Service Intervals Oil Change Interval: Every 3,000-5,000 km (2,000-3,000 miles) or annually Valve Adjustment Interval: Every 5,000-10,000 km (3,000-6,000 miles) Spark Plug Replacement: Every 5,000-10,000 km (3,000-6,000 miles) Carburetor Sync Interval: Every 10,000-15,000 km (6,000-9,000 miles) or as needed Fluid Specifications Brake Fluid Type: DOT 3 or DOT 4 (check caliper manufacturer specifications) Final Drive Oil Viscosity: SAE 90 Gear Oil (API GL-4) Known Issues Common Wear Items: Fork seals, swingarm pivot bearings, steering head bearings, clutch wear, output shaft seal leaks Electrical Quirks: Aging wiring harnesses, regulator/rectifier failures, aging battery terminals Engine Considerations: Oil leaks from the front of the engine (timing chain cover), clutch plate wear, potential for pushrod tube seal leaks Part Numbers Oil Filter Part Number: BMW Part No. 11 42 1 266 485 (or equivalent aftermarket) 📚 Vehicle History Brand Heritage Bmw Motorcycle History: BMW has a long and storied history in motorcycle manufacturing, known for engineering excellence, durability, and innovation, particularly in boxer engine technology. Model Evolution R90 Series Development: The R90/6 was an evolution of BMW's successful large-displacement boxer twins, offering a blend of performance, comfort, and reliability for both commuting and touring. Production Production Years: 1973-1976 Manufacturing Location: Berlin, Germany (Spandau plant) Production Numbers: Approximately 15,549...