Positioning:
The BMW R90 series was positioned as a premium, large-displacement motorcycle offering touring comfort and robust performance, a successor to earlier R series models.
Competitors:
Competed with other large-displacement European motorcycles and some Japanese offerings emphasizing performance and build quality.
Highlights:
Iconic BMW boxer twin engine, shaft drive, comfortable ergonomics, durable construction.
Value:
Provides essential technical data and procedures to maintain, repair, and restore the classic BMW R90, preserving its performance and value.
Primary Coverage:
Full Service, Repair, Rebuild, Refurbishment, Restoration
Diagnostic Coverage:
Diagnostic procedures included
Estimated Page Count:
Refer to product listing for exact page count, typically extensive for full service manuals.
Details:
A comprehensive manual will contain hundreds of pages to cover all aspects of the vehicle's repair and maintenance.
Type:
Full Service Repair Manual
Format:
Digital (likely PDF, check product listing for specifics)
Engine:
Complete engine overhaul, including disassembly, inspection, assembly, timing, valve adjustment, carburetor tuning.
Transmission:
Gearbox disassembly, inspection, repair, and adjustment, including clutch and final drive.
Chassis And Suspension:
Front fork service, shock absorber replacement, steering head bearing maintenance, swingarm bearing inspection.
Brakes:
Brake system servicing (drum/disc, depending on specific R90 variant), fluid replacement, caliper/master cylinder repair.
Electrical System:
Wiring diagrams, ignition system troubleshooting, lighting, battery, charging system (alternator/generator) repair.
Fuel System:
Fuel tank servicing, fuel line inspection, carburetor servicing and synchronization.
Bodywork And Frame:
Frame inspection, minor bodywork repair guidance, component removal and installation.
Exhaust System:
Inspection, repair, and replacement of exhaust components.
Cooling System:
While air-cooled, the manual may cover management of engine temperature and related components.
Maintenance:
Regular service checks, oil changes, filter replacements, lubrication points, tune-up procedures.
Troubleshooting:
Step-by-step diagnostic guides for common and uncommon issues.
Repair:
Detailed instructions for component repair and replacement across all major systems.
Rebuild Refurbish:
Comprehensive guides for engine, transmission, and other major component overhauls.
Special Tools:
Lists and describes the use of special tools required for specific repair procedures.
Assembly Disassembly:
Step-by-step instructions for complete disassembly and reassembly of all major components.
Depth:
Expert level, suitable for professional mechanics and serious enthusiasts. Covers detailed specifications, tolerances, and torque values.
Diagnostic Charts:
Includes comprehensive diagnostic flowcharts and symptom-based troubleshooting tables.
Torque Specifications:
Detailed torque specifications for all critical fasteners.
File Type:
Digital (likely PDF)
Searchability:
Digital PDFs are typically searchable, allowing for quick access to specific information.
Quality:
High resolution scans ensuring legibility of diagrams and text.
Binding:
Not applicable for digital format; if printed, would be a professional binding.
Paper:
Not applicable for digital format; if printed, would be durable workshop paper.
Engine Type:
Air-cooled, horizontally opposed two-cylinder boxer engine
Engine Displacement:
Approximately 897 cc (specific variant may vary slightly)
Bore X Stroke:
90 mm x 70.6 mm (typical for R90/6, R90S)
Horsepower:
Approximately 60-70 hp at 6500 rpm (depending on model R90/6 vs R90S)
Torque:
Approximately 75 Nm at 5000 rpm (depending on model)
Carburetors:
Typically dual Dell'Orto or Bing carburetors (e.g., 32mm or 36mm)
Ignition Type:
Battery-coil ignition, possibly with electronic ignition conversion options discussed.
Cooling Method:
Air-cooled
Layout:
Horizontally opposed (boxer)
Valvetrain Type:
Overhead valves (OHV), pushrod actuated.
Oil Change Interval:
Typically every 3,000-5,000 km or annually. Specific interval detailed in manual.
Valve Adjustment Interval:
Recommended every 5,000-10,000 km. Precise interval and procedure covered in manual.
Engine Oil Type:
SAE 20W-50 or SAE 10W-40 motorcycle specific oil is common. Refer to manual for exact BMW recommendation.
Gearbox Oil Type:
Hypoid gear oil, e.g., SAE 80W-90. Manual will specify precise grade.
Brake Fluid Type:
DOT 3 or DOT 4 brake fluid for hydraulic systems. Manual will specify.
Common Wear Items:
Wear on steering head bearings, front fork seals, clutch plates, and valve guides.
Electrical Gremlins:
Older wiring harnesses can degrade, leading to intermittent electrical issues. Manual provides diagnostic paths.
Carburetor Synchronization:
Requires regular synchronization for optimal running. Covered in detail.
Engine Oil Capacity:
Approximately 2.5 - 3.0 liters (check manual for exact amount).
Heritage:
BMW Motorrad has a long history of producing high-quality motorcycles, renowned for engineering, reliability, and innovation.
Evolution:
The R90 series (R90/6 and R90S) represented a significant step up in performance and luxury from earlier boxer twins, with the R90S being the sportier, more powerful variant.
Key Variants:
R90/6 (standard) and R90S (sport, with fairing and dual disc brakes).
Production Years:
Production for the R90 series typically ran from 1973 to 1976, with the 1991 designation in the manual likely referring to a specific build or late-model reference within the broader R90 family or a misunderstanding of the model year.
