🏷️ Basic Information Identification Make: BMW Model: R90 Year: 1985 Vehicle Type: Motorcycle Codes Chassis Code: R90/6, R90S (Note: Manual likely covers both variants if released in 1985, though R90S was typically earlier. 1985 is a very late model year for R90 designation, suggesting potential regional variants or a typo in product naming. Assuming the manual is for a model branded as R90 in 1985.) 👋 Introduction Market Position Positioning: The BMW R90 series, particularly the R90S, was positioned as a premium sport touring motorcycle in its era, known for its performance, engineering quality, and comfortable ride. This manual targets owners and enthusiasts dedicated to maintaining or restoring these iconic machines. Competitive Analysis Competitors: In its segment, the R90 competed with other high-performance motorcycles from European and Japanese manufacturers, emphasizing rider comfort, build quality, and long-distance capability. Its shaft drive and boxer engine were distinctive features. Key Features Manual Highlights: Encompasses all aspects of R90 ownership, from routine upkeep to in-depth engine rebuilds. Features detailed diagrams, clear procedural steps, and essential technical data, making it an indispensable resource for preserving the legacy of the R90. 📋 Manual Details Coverage Areas Engine Coverage: Complete overhaul, tuning, fuel system, ignition system, lubrication, cooling (air-cooled) Transmission Coverage: Gearbox disassembly, assembly, shifting mechanism, clutch service Chassis Coverage: Frame, suspension (front fork, rear shocks), steering head bearings, wheels, brakes (disc and drum), final drive Electrical Coverage: Wiring diagrams, lighting system, ignition system components, battery, charging system, starter motor, instrumentation Bodywork Coverage: Fairings (if applicable to R90S), fuel tank, seat, fenders, exhaust system, mounting hardware Diagnostic Coverage: Troubleshooting guides, fault finding procedures, common issues and solutions Page Count Estimated Page Count: 300-500 pages (typical for a comprehensive service manual of this era and scope) Manual Type Type: Full Service and Repair Manual Language Language: English Format Format: Digital (likely PDF), potentially available as a printed reproduction 📖 Manual Coverage Systems Covered All Systems: Engine, Drivetrain, Chassis, Electrical, Braking, Fuel, Ignition, Lubrication, Suspension, Steering, Wheels and Tires, Bodywork, Troubleshooting, Maintenance Procedures Included Maintenance Procedures: Oil changes, filter replacements, spark plug service, chain adjustment, brake adjustments, valve clearance checks, steering head bearing adjustment Repair Procedures: Engine rebuild, gearbox repair, carburetor overhaul, fork seal replacement, brake caliper rebuild, final drive maintenance Diagnostic Procedures: Troubleshooting common performance issues, ignition timing checks, carburetor synchronization, electrical system fault finding Technical Depth Depth: Comprehensive, from basic scheduled maintenance to complete engine and transmission overhauls. Includes detailed specifications, torque values, and step-by-step instructions suitable for home mechanics and professional technicians. 📊 Manual Specifications File Format Digital Format: PDF (Searchable text, high-resolution diagrams, printable pages) Print Quality Print Quality: N/A (for digital), High-resolution scans for printable versions, clear and legible diagrams Binding Type Binding Type: N/A (for digital), Perfect bound or spiral bound (for printed reproductions) Paper Type Paper Type: N/A (for digital), High-quality matte or glossy paper for printed versions ⚙️ Engine Specifications Primary Engine Engine Type: Air-cooled, four-stroke, horizontally opposed twin-cylinder (Boxer) Displacement: 897 cc (for R90/6 and R90S) Bore X Stroke: 90 mm x 70.6 mm Compression Ratio: 9.5:1 (R90S), 8.2:1 (R90/6) Valvetrain: Overhead valves (OHV), pushrod actuated, 2 valves per cylinder Performance Horsepower: 67 hp @ 7000 rpm (R90S), 60 hp @ 6500 rpm (R90/6) Torque: 75 Nm @ 5500 rpm (R90S), 70 Nm @ 5000 rpm (R90/6) Fuel System Carburetors: Dell'Orto PHM 40 (R90S), Bing 32mm CV (R90/6) Fuel Type: Unleaded gasoline (Octane rating as per manual recommendations, typically 95 RON) Lubrication Oil Capacity: Approx. 4 liters (including filter) Oil Type Recommendation: SAE 20W/50 or 10W/40 motorcycle specific oil (check manual for precise specification, e.g., API SG or higher) Ignition Ignition System: Breaker point ignition with dual spark plugs per cylinder (R90S), single spark ignition (R90/6) 🔧 Transmission Standard Type: 5-speed constant mesh, sequential manual gearbox Optional Optional Gearbox: N/A (Standard across R90 models) Features Drive Type: Shaft drive (enclosed drive shaft) Clutch Type: Single dry plate clutch (R90/6), Twin dry plate clutch (R90S) Fluid Specifications Gearbox Oil Type: SAE 80W/90 hypoid gear oil (API GL-5 recommended) 📐 Dimensions Exterior Length: Approx. 2200 mm (varies slightly by model variant) Width: Approx. 850 mm (including handlebars) Height: Approx. 1200 mm (to top of handlebars) Wheelbase: Approx. 1465 mm Weights Dry Weight: Approx. 200 kg (R90/6), 212 kg (R90S) Gross Vehicle Weight: Approx. 390 kg Cargo Fuel Tank Capacity: 24 liters (including reserve) 🛡️ Safety Features Ratings Safety Standard: N/A (Motorcycle safety ratings were not standardized as they are for cars today. Focus is on operational safety and rider control.) Active Features Braking System: Front: Hydraulic disc brake (dual discs on R90S, single disc on R90/6), Rear: Drum brake Suspension Type: Front: Telescopic fork with hydraulic damping, Rear: Swingarm with dual shock absorbers Passive Features Frame Construction: Steel tube duplex cradle frame Lighting: Halogen headlight, taillight, brake light, turn signals 💡 Technology...