🏷️ Basic Information Identification Make: BMW Model: R90 Year: 1987 Codes Engine Code Variant: R90/6 (likely, given the year and model designation historically) 👋 Introduction Market Position Target Audience: BMW R90 owners, enthusiasts, and independent mechanics seeking in-depth maintenance and repair knowledge. Competitive Analysis Manual Value Proposition: Provides essential, factory-level information often unavailable in generic repair guides, enabling confident DIY maintenance and repairs. Key Features Comprehensiveness: Covers all major mechanical and electrical systems of the 1987 BMW R90 model. Accessibility: Digital format allows for easy searching, printing of specific sections, and access on various devices. 📋 Manual Details Coverage Areas Manual Type: Service and Repair Manual Language: English Format: Downloadable Digital File (PDF assumed) Page Count Estimated Page Count: 300-500 (typical for comprehensive motorcycle service manuals of this era) 📖 Manual Coverage Systems Covered Engine Overhaul: Complete engine disassembly, inspection, repair, and reassembly procedures for the R90 series engine. Fuel System: Carburetor tuning, cleaning, rebuilding (likely Bing carburetors), fuel tank, fuel lines, and petcock service. Ignition System: Ignition timing, spark plugs, ignition coils, breaker points (if applicable), electronic ignition components (if upgraded), and troubleshooting. Transmission And Drivetrain: Gearbox disassembly, inspection, repair, clutch operation, driveshaft, final drive maintenance, and lubrication. Brakes System: Hydraulic brake system service (master cylinder, calipers, lines), pad replacement, brake fluid flush and bleed procedures, parking brake (if applicable). Suspension And Steering: Front fork service (oil changes, seal replacement, spring inspection), rear shock absorber maintenance, steering head bearing adjustment, and wheel bearing service. Electrical System: Wiring diagrams, battery maintenance, charging system (alternator/generator), starter motor, lighting circuits, switches, and fuses. Chassis And Frame: Frame inspection, swingarm maintenance, center stand and side stand service. Bodywork And Trim: Fairing removal/installation, seat maintenance, fender and body panel service. Instrumentation: Speedometer, tachometer, warning lights, and associated sensor/cable service. Procedures Included Routine Maintenance: Oil and filter changes, spark plug replacement, chain adjustment (if applicable), brake adjustments, lubrication points. Troubleshooting Guides: Diagnostic charts and procedures for common mechanical and electrical issues. Component Rebuilds: Detailed instructions for rebuilding carburetors, brake calipers, master cylinders, and gearbox components. Timing Adjustments: Ignition timing and valve clearance adjustments. Wheel And Tire Service: Tire pressure checks, wheel removal/installation, spoke tensioning (if applicable). Rear Drive Maintenance: Service of the final drive unit, including lubrication and potential seal replacement. Carburetor Sync: Detailed steps for synchronizing dual carburetors for optimal engine performance. Technical Depth Depth Of Coverage: Comprehensive, covering everything from basic owner maintenance to complete engine and transmission overhauls. Diagnostic Information: Detailed diagnostic procedures and specifications for diagnosing faults. Torque Specifications: Precise torque values for all critical fasteners. Schematics And Diagrams: Includes detailed exploded views, wiring diagrams, and system schematics. Specification Tables: Includes comprehensive tables for all specifications, clearances, fluid capacities, and torque values. 📊 Manual Specifications File Format File Type: PDF (Portable Document Format) Searchability: Likely text-searchable if originally digitized from a well-scanned manual. Print Quality Print Readability: Depends on original source quality, but intended for clear printing and on-screen viewing. Binding Type Binding For Download: N/A (Digital Download) Paper Type Paper Type For Download: N/A (Digital Download) ⚙️ Engine Specifications Primary Engine Engine Type: Air-cooled, four-stroke, horizontally opposed twin-cylinder boxer engine. Displacement: 900cc (approximately 897cc) Bore X Stroke: Approximately 90 mm x 70.6 mm (exact figures may vary slightly by specific R90 variant). Compression Ratio: Typically around 8.2:1 to 9.5:1 depending on specific model variant (e.g., R90/6). Performance Horsepower: Approximately 60-65 HP @ 7000 RPM (for R90/6, figures may vary). Torque: Approximately 70-75 Nm @ 5500 RPM (for R90/6, figures may vary). Fuel System Carburetor Type: Dual Bing 32mm or 36mm constant velocity carburetors (common for R90/6). Fuel Type: Unleaded gasoline (premium recommended, 91 octane or higher). Lubrication Oil Capacity: Approximately 2.5 - 3.0 Liters (including filter, check manual for exact figure). Oil Type Recommendation: SAE 20W-50 or 10W-40 motorcycle specific oil meeting API SG or higher. 🔧 Transmission Standard Transmission Type: 5-speed manual gearbox. Optional Optional Transmission: N/A (5-speed manual was standard). Features Final Drive: Shaft drive (BMW's signature enclosed driveshaft). Clutch Type: Dry single-plate clutch (actuated by cable). Fluid Specifications Gearbox Oil Type: EP 80W-90 gear oil (check manual for specific BMW recommendation). 📐 Dimensions Exterior Wheelbase: Approximately 1460 mm (57.5 inches) - typical for R90/6. Seat Height: Approximately 800 mm (31.5 inches) - rider seat height. Weights Dry Weight: Approximately 200-215 kg (440-475 lbs) - depending on exact model and equipment. Gross Vehicle Weight Rating: Not typically specified for motorcycles in this manner, but payload capacity is relevant. Wheels And Tires Front Tire Size: 3.50-18 or 100/90-18 (typical). Rear Tire Size: 4.00-18 or 120/90-18 (typical). Front Wheel Size: 18 x 2.15 or 18 x 2.50 (typical). Rear Wheel Size: 18 x 2.50 or 18 x 3.00 (typical). 🛡️ Safety Features Ratings Crash Test Results: N/A (motorcycle safety ratings differ from automotive; manual covers mechanical safety systems). Active Features...