Category:
Dual-sport motorcycle
Segment:
Adventure touring, off-road capable touring
Competitors 1985:
Honda Transalp (later), Yamaha Tenere, Suzuki DR series, Kawasaki KLR
Engine Type:
Air-cooled boxer twin
Drive System:
Shaft drive
Suspension R100Gs:
Monolever rear suspension (single-sided swingarm)
Suspension R80Gs:
Traditional twin rear shock absorbers
Durability:
Renowned for robustness and long-distance touring capability
Off Road Capability:
Designed with significant off-road prowess for its era
Engine Mechanical:
Full overhaul, cylinder head, pistons, crankshaft, timing, valve train
Engine Management:
Ignition system, fuel injection (K-Jetronic for R100, Bing carburetors for R80), starting system, charging system
Transmission Gearbox:
Disassembly, assembly, gear inspection, shifting mechanism
Drivetrain:
Clutch (single plate dry), driveshaft, universal joints, rear axle, final drive
Frame And Suspension:
Frame inspection and repair, front fork (telescopic), rear swingarm, shock absorbers (Monolever for R100GS, twin shocks for R80GS)
Braking System:
Front and rear brake systems (disc brakes), hydraulic lines, master cylinders, calipers, bleeding procedures
Electrical System:
Wiring diagrams, lighting system, instrumentation, battery, starter motor, alternator, ignition coils, fuses
Fuel And Exhaust:
Fuel tank, fuel pump, fuel lines, carburetor overhaul (R80GS), K-Jetronic fuel injection troubleshooting (R100GS), exhaust system components
Routine Maintenance:
Oil changes, filter replacement, spark plug checks, chain adjustment (if applicable, though these are shaft-driven), valve clearance adjustments, lubrication points
Component Overhaul:
Complete engine rebuild, gearbox rebuild, carburetor servicing, fuel injection system servicing, brake caliper overhaul, suspension component rebuild
Troubleshooting Diagnostics:
Step-by-step diagnostic procedures for common starting, running, and electrical issues, fault finding charts
Torque Specifications:
Detailed torque values for all critical fasteners and components
Wiring Diagrams:
Comprehensive electrical schematics for all systems
Special Tools:
Identification and usage of BMW-specific tools required for certain procedures
Depth:
Comprehensive: Covers everything from basic maintenance to full engine and transmission rebuilds, including advanced diagnostics and electrical system repair.
Type:
Four-stroke, air-cooled boxer twin
Bore X Stroke R80:
80.0 mm x 78.0 mm
Bore X Stroke R100:
94.0 mm x 70.5 mm
Displacement R80:
797.5 cc
Displacement R100:
980 cc
Compression Ratio R80:
8.2:1
Compression Ratio R100:
8.5:1
Horsepower R80:
50 hp @ 6500 rpm (approx.)
Horsepower R100:
65 hp @ 7250 rpm (approx.)
Torque R80:
57 Nm @ 5000 rpm (approx.)
Torque R100:
78 Nm @ 6000 rpm (approx.)
R80Gs Carburetor:
2 x Bing 32mm constant-vacuum carburetors
R100Gs Fuel Injection:
Bosch L-Jetronic (K-Jetronic) fuel injection system
Fuel Type:
Unleaded gasoline (91 octane or higher)
System:
Breakerless electronic ignition
Safety Rating:
N/A (Motorcycle safety standards of the era)
Brakes:
Dual 285mm front discs, single 200mm rear disc (R100GS has dual front discs as standard, R80GS often single front disc)
Suspension Stability:
Paralever (on later R100GS models, not 1985) / Monolever (on 1985 R100GS) and well-engineered conventional suspension contribute to stability.
Frame Strength:
Robust steel tube frame construction
Lighting:
Halogen headlamp, integrated turn signals and taillight
Oil Change Engine:
Every 5,000 - 10,000 km or annually
Oil Change Final Drive:
Every 10,000 - 20,000 km
Valve Clearance Check:
Every 10,000 km
Spark Plug Check:
Every 10,000 km
Engine Oil Type:
SAE 20W-50 or SAE 15W-40 motorcycle-specific oil (API SG or higher)
Engine Oil Capacity:
Approx. 2.5 - 3.0 liters (depending on filter change)
Final Drive Oil Type:
SAE 80W-90 hypoid gear oil (API GL-5)
Final Drive Oil Capacity:
Approx. 0.25 liters
Clutch Fluid Type:
DOT 4 (if hydraulic)
Oil Leaks:
Common around cylinder head base gaskets and pushrod tubes.
Clutch Slave Cylinder:
Potential for leaks or failure on hydraulically actuated clutches.
Electrical Connections:
Corrosion or loose connections, especially in the charging system and lighting.
Fuel Injection R100Gs:
K-Jetronic can be sensitive to air leaks and requires careful tuning. Injector issues can occur.
Monolever Bearing:
Wear in the Monolever pivot bearing (R100GS) can lead to handling issues.
Bmw Motorrad Legacy:
BMW Motorrad has a long history of producing durable and reliable motorcycles, particularly known for their boxer-twin engines and shaft drive.
R Series Origin:
The R80GS and R100GS are descendants of the original R80G/S, which defined the dual-sport segment in the early 1980s.
Gs Development:
The 'GS' designation stands for 'Gelände/Straße' (Off-road/Street), highlighting the bikes' dual-purpose design. The R100GS introduced the revolutionary Monolever rear suspension system.
Production Years R80Gs:
1980-1987 (G/S), 1987-1990 (GS)
Production Years R100Gs:
1987-1996 (though 1985 is specifically covered by the manual, models from '87 onwards refined the design)
Manufacturing Location:
Berlin, Germany (BMW Motorrad factory)
