Engine:
All engine types, including teardown, assembly, tuning, and component diagnostics.
Transmission:
Manual and Automatic transmission service, repair, and overhaul procedures.
Drivetrain:
Driveshaft, differential, axles, and related components.
Brakes:
Hydraulic systems, ABS (if equipped), disc/drum brake service, components.
Suspension:
Front and rear suspension components, shock absorbers, springs, alignment.
Steering:
Steering rack, power steering system, components, and alignment.
Electrical:
Wiring diagrams, starter, alternator, battery, lighting, ignition system, fuse/relay diagnostics.
Fuel System:
Fuel pump, injectors, fuel lines, tank, emissions control systems.
Cooling System:
Radiator, thermostat, coolant flow, water pump, fan.
Exhaust System:
Mufflers, catalytic converters, pipes, hangers, emissions control.
Body And Chassis:
Body panels, doors, windows, interior trim, chassis components.
HVAC:
Heating, Ventilation, and Air Conditioning system service and repair.
Instrumentation:
Speedometer, tachometer, fuel gauge, warning lights, and their electrical systems.
Routine Maintenance:
Oil changes, filter replacements, spark plug service, fluid checks and top-offs.
Troubleshooting:
Diagnostic procedures for common and uncommon issues across all systems.
Component Replacement:
Step-by-step guides for replacing individual parts and sub-assemblies.
Rebuilding And Overhaul:
Detailed instructions for engine, transmission, and differential rebuilds.
Electrical Diagnostics:
Using multimeters, oscilloscopes, and wiring diagrams for fault finding.
Calibration And Adjustment:
Valve adjustments, idle speed settings, ignition timing, brake bleeding.
Body Repair:
Dent repair, panel replacement, rust mitigation, glass replacement.
Painting And Refinishing:
Procedures for paint preparation, application, and finishing.
Wheel And Tire Service:
Tire pressure, wheel balancing, bearing service, spoke tensioning (if applicable).
Depth:
Comprehensive, from basic owner maintenance to full engine/transmission rebuilds and advanced diagnostics.
Wiring Diagrams:
Includes detailed electrical schematics for all vehicle systems.
Torque Specifications:
Provides exact torque values for all critical fasteners and engine components.
Diagnostic Charts:
Includes flowcharts and tables for systematic troubleshooting of common faults.
Special Tools:
Lists any specialized tools or equipment required for specific repair procedures.
Engine Type:
Air-cooled, Boxer Twin
Displacement:
897 cc (897 cubic centimeters)
Bore X Stroke:
90 mm x 70.6 mm
Valve Train:
OHV (Overhead Valve), Pushrod actuated, 2 valves per cylinder.
Horsepower:
Approx. 60 HP (45 kW) at 6,250 RPM
Torque:
Approx. 76 Nm (56 lb-ft) at 5,000 RPM
Fuel Delivery:
Dual Dell'Orto PHM 38 BS or PHM 38 PS Carburetors
Ignition Type:
Battery-coil ignition with dual spark plugs per cylinder.
Oil Type:
SAE 20W-50 or SAE 15W-40 (mineral or synthetic motorcycle specific)
Oil Capacity:
Approx. 2.7 liters (2.8 US qt) with filter change.
Oil Change Interval:
Every 5,000 km (3,000 miles) or annually.
Valve Adjustment Interval:
Every 10,000 km (6,000 miles).
Spark Plug Replacement:
Every 10,000 km (6,000 miles), inspect every 5,000 km.
Gearbox Oil Change:
Every 20,000 km (12,000 miles).
Final Drive Oil:
SAE 75W-90 or SAE 80W-90 GL-5 (Hypoid Gear Oil)
Coolant Type:
N/A (Air-cooled engine)
Common Issues:
Carburetor synchronization, worn output shaft seal, aging electrical components, weak clutch springs, oil leaks from engine casing and transmission.
Preventative Maintenance Focus:
Regularly check and adjust valve clearances, maintain correct idle speed, ensure proper carburetor tuning, inspect the drive shaft boot for tears.
Bmw Motorcycle History:
BMW has a long and storied history in motorcycle manufacturing, dating back to 1923. Known for engineering excellence, shaft drive, and boxer engines.
R Series Lineage:
The R90 is part of the iconic BMW R series, evolving from earlier models like the R75 and leading to later variants. It represents a performance-oriented touring motorcycle of its era.
Production Period:
The R90/6 was produced from 1973-1976. The R90 model year is likely a reference to a later iteration or a common misidentification for models like the R100RS or R100RT which are similar in concept.
Specific Model Clarification:
The 'BMW R90 1988' product name is potentially a misnomer as the R90 model line (R90/6, R90S) concluded production in 1976. This manual may cover the R100 series from 1988, or it is a generic title for a manual covering R90 models from their original production run and subsequent repairs.
