Segment:
Iconic German motorcycle manufacturer's air-cooled boxer twin platform
Target Audience:
BMW motorcycle owners, mechanics, restorers, and enthusiasts
Value Proposition:
Provides essential, detailed technical information for maintaining and repairing BMW's highly regarded air-cooled boxer twins, crucial for preserving their longevity and performance.
Diagrams Illustrations:
Likely includes detailed exploded diagrams and schematic illustrations essential for assembly and disassembly.
Diagnostic Tables:
Essential for identifying and rectifying common issues specific to these models.
Models Covered:
All R80, R90, and R100 series models produced in or around 1990
Engines Covered:
All boxer twin engine variants (e.g., 797cc, 897cc, 971cc, 980cc, 1000cc)
Transmissions Covered:
All manual transmissions for the specified models
Trim Levels Covered:
All trim levels and variants (e.g., Standard, S, RS, RT, GS, R)
Estimated Page Count:
400-600 (typical for comprehensive workshop manuals of this era)
Type:
Workshop Repair and Service Manual
Engine Mechanical:
Engine overhaul, cylinder head, piston, crankshaft, camshaft, timing, valve clearance adjustment
Fuel System:
Carburetor tuning and overhaul (e.g., Bing), fuel pump, fuel lines, fuel tank
Ignition System:
Ignition timing, spark plugs, coils, ignition control unit
Electrical System:
Wiring diagrams, alternator, starter motor, battery, lighting, instrumentation, switches
Transmission Drivetrain:
Gearbox overhaul, clutch operation and adjustment, driveshaft, final drive
Suspension:
Front forks (telescopic), rear swingarm, shock absorbers, linkage (if applicable)
Brakes:
Brake caliper service, master cylinder, brake lines, pad replacement, bleeding procedures
Wheels Tires:
Wheel bearing replacement, tire pressure, rim maintenance
Chassis Frame:
Frame inspection, steering head bearing replacement
Bodywork Cosmetics:
Fairing removal and installation, seat, fuel tank removal, fenders
Maintenance:
Scheduled maintenance, oil changes, filter replacements, lubrication points, adjustments
Troubleshooting:
Diagnostic charts, common problems and their solutions, symptom-based diagnosis
Repair:
Step-by-step instructions for component disassembly, reassembly, and repair
Overhaul:
Complete engine, transmission, and component overhaul procedures
Diagnostics:
Electrical system diagnostics, engine performance testing
Depth:
Comprehensive (from basic maintenance to complete engine rebuilds and electrical system diagnostics)
Detail Level:
Detailed torque specifications, clearances, tolerances, and assembly sequences
Type:
Air-cooled, four-stroke boxer twin
Displacement Range:
797cc (R80) to 1000cc (R100 series)
Bore X Stroke Examples:
R80: 82mm x 74.6mm; R90S: 90mm x 70.6mm; R100GS: 94mm x 70.6mm
Compression Ratio Range:
Typically 8.5:1 to 9.5:1 depending on model and tune
Power Output Range:
Approximately 50 HP (R80) to 70 HP (R100RS/RT) at 6500-7000 RPM
Torque Output Range:
Approximately 57 Nm (R80) to 75 Nm (R100 series) at 4000-5000 RPM
Carburetors Common:
Dual Bing constant velocity carburetors (e.g., 32mm, 40mm depending on model)
Fuel Type:
Unleaded gasoline (91-95 RON recommended)
Ignition Type:
Electronic ignition (breakerless system)
Oil System:
Wet sump lubrication with oil cooler on most models
Type:
5-speed constant mesh manual transmission
Optional Gearbox:
N/A (all models typically used the same 5-speed unit, though gear ratios might vary slightly)
Clutch Type:
Single dry plate clutch, cable operated
Final Drive:
Shaft drive (enclosed drive shaft)
Wheelbase Range:
Approx. 1440mm - 1490mm (varies by model, e.g., GS longer)
Dry Weight Range:
Approx. 195kg - 230kg (varies by model, e.g., RT heavier, GS lighter than RS)
Gross Vehicle Weight Rating:
Typically around 370kg - 400kg
Crash Test Ratings:
N/A (Motorcycles of this era were not subject to standardized crash testing like cars)
Braking System:
Dual disc front brakes (size varies by model, e.g., 285mm), single disc rear brake (or drum on earlier/smaller models).
Anti Lock Brakes:
ABS was an option on some later R100 models (e.g., R100RT), but not standard across all
Lighting:
Halogen headlamp, LED taillight/brake light (often aftermarket upgrades)
Oil Change Interval:
Typically every 5,000 - 7,500 km (3,000 - 5,000 miles) or annually, whichever comes first. Check manual for specifics.
Valve Adjustment Interval:
Every 10,000 - 12,000 km (6,000 - 7,500 miles). Often done every other oil change.
Spark Plug Replacement:
Every 10,000 - 15,000 km (6,000 - 10,000 miles)
Engine Oil Type:
Multi-viscosity oil, SAE 20W-50 or 10W-40 recommended for most climates. API SG or higher rating.
Engine Oil Capacity:
Approx. 2.5 liters (2.6 US quarts) with filter change
Transmission Oil Type:
Gear oil, SAE 80W/90 GL-5
Transmission Oil Capacity:
Approx. 0.85 liters (0.9 US quarts)
Final Drive Oil Type:
Gear oil, SAE 80W/90 GL-5
Final Drive Oil Capacity:
Approx. 0.25 liters (0.26 US quarts)
Brake Fluid Type:
DOT 3 or DOT 4 brake fluid
Ignition Coil Failure:
Coils can fail, leading to misfires or no spark. The manual will detail testing procedures.
Carburetor Icing/Gumming:
Bing carburetors can be sensitive to fuel quality and require regular cleaning and adjustment. Manual covers disassembly.
Pushrod Tube Seals:
Leaking pushrod tube seals are a common characteristic, often addressed during valve adjustments. Manual provides seal replacement instructions.
Clutch Actuation:
Cable stretching or linkage wear can affect clutch feel. Manual details adjustment and replacement.
Wiring Loom Degradation:
Older wiring can become brittle. Manual's wiring diagrams are crucial for troubleshooting and repairs.
Bmw Motorrad Legacy:
BMW Motorrad has a long history dating back to 1923, with the boxer twin engine being a core design principle for much of that time.
Airhead Lineage:
The R80, R90, and R100 models represent the evolution of BMW's 'Airhead' boxer twin series, building upon earlier designs and incorporating technological advancements.
Key Variants:
R90S (performance-oriented, dual disc, twin plug), R100RS (fully faired sport-tourer), R100RT (touring focus with large fairing and luggage), R100GS (dual-sport/adventure variant).
Production Era:
The Airhead series spanned from the 1970s through the early 1990s, with the 1990 model year falling within the later stages of this development.
Motorcycle Of The Year:
While specific awards for the 1990 models might not be widely documented, the R-series is consistently recognized for its engineering, durability, and unique character.
Owner Satisfaction:
High owner satisfaction historically, particularly for the long-distance touring and adventure variants, due to their robust build and reliability when properly maintained.
Emissions Standards:
Compliance with prevailing emissions standards for the respective markets in 1990.
