Description:
The BMW R80GS and R100GS are iconic adventure touring motorcycles renowned for their durability, off-road capability, and boxer-twin engine character. They represent a significant period in BMW's dual-sport motorcycle development.
Competitors:
Competitors of the era included motorcycles like the Yamaha XT500/XT600, Honda XL series, Kawasaki KLR series, and Suzuki DR series, though the BMWs often occupied a more premium and long-distance touring segment.
Features:
Shaft drive, horizontally opposed boxer twin engines, long-travel suspension, robust construction, excellent touring capabilities, and significant off-road potential. The R100GS notably introduced the Paralever rear suspension system for improved handling.
Engine:
Comprehensive coverage including air-cooled boxer twin engine disassembly, assembly, tuning, and troubleshooting.
Transmission:
Detailed procedures for 5-speed transmission (Type 247) maintenance, repair, and overhaul.
Drivetrain:
Shaft drive system, universal joint, final drive unit maintenance and repair.
Suspension:
Front telescopic forks (including optional USD forks for some R100GS models), rear Monolever or Paralever swingarm system, shock absorber servicing, fork seal replacement, and adjustments.
Brakes:
Front and rear disc brake systems, caliper overhaul, master cylinder repair, brake line replacement, and bleeding procedures.
Electrical:
Wiring diagrams, ignition system (points or electronic), charging system (alternator, regulator), lighting, starter system, and instrument cluster troubleshooting.
Fuel System:
Carburetor servicing (Bing type), fuel pump, fuel lines, and fuel tank maintenance.
Exhaust System:
Exhaust manifold, mufflers, and mounting hardware inspection and replacement.
Bodywork:
Fairing (often optional), fuel tank, seat, fenders, and side panel removal and installation.
Maintenance:
Scheduled maintenance tasks, oil changes, filter replacements, spark plug checks, valve clearance adjustments, and lubrication points.
Troubleshooting:
Systematic diagnostic steps for common and complex issues, fault finding guides.
Repair:
Step-by-step instructions for component disassembly, repair, and reassembly.
Overhaul:
Complete engine, transmission, and final drive rebuild procedures.
Adjustments:
Carburetor synchronization, ignition timing, clutch adjustment, and brake lever free play.
Depth:
Comprehensive, covering basic routine maintenance to full engine and transmission rebuilds, including diagnostic charts and detailed specifications.
Engine Type:
Air-cooled, four-stroke, horizontally opposed twin-cylinder boxer engine.
Bore X Stroke R80:
80.0 mm x 78.0 mm
Bore X Stroke R100:
94.0 mm x 70.7 mm
Displacement R80:
797.5 cc
Displacement R100:
980 cc
Compression Ratio:
8.2:1 (typical, may vary slightly by year/model)
Horsepower R80:
50 hp (37 kW) at 6,500 rpm (approx.)
Horsepower R100:
65 hp (48 kW) at 7,250 rpm (approx.)
Torque R80:
57 Nm (42 lb-ft) at 5,000 rpm (approx.)
Torque R100:
74 Nm (55 lb-ft) at 5,500 rpm (approx.)
Carburetors:
2 x Bing 32mm (R80GS), 2 x Bing 40mm (R100GS)
Fuel Type:
Unleaded gasoline (minimum 90 RON / 87 AKI)
Fuel Capacity:
Approx. 19-21 liters (including reserve, depending on tank size)
Type:
5-speed constant mesh gearbox (Type 247)
Clutch:
Single dry plate, hydraulically actuated
Final Drive:
Shaft drive with enclosed universal joint and final reduction gear.
Transmission Fluid:
SAE 80W/90 hypoid gear oil (API GL-5 recommended)
Safety Standards:
Manufactured to meet relevant European and international motorcycle safety standards of the period. No formal NCAP ratings for motorcycles.
Braking System:
Dual disc front brakes (single disc on some earlier R80GS models) and single disc rear brake, often with Brembo components. ABS was not standard on these models.
Frame Construction:
Steel tube duplex cradle frame for rigidity and durability.
Oil Change Interval:
Typically every 5,000 km or annually. Refer to manual for exact specifications.
Valve Clearance Interval:
Every 10,000 km or annually.
Spark Plug Replacement:
Every 10,000 - 20,000 km, depending on type.
Engine Oil Type:
Mineral or semi-synthetic motorcycle oil, SAE 20W-40 or 20W-50 recommended (API SG or higher).
Engine Oil Capacity:
Approx. 2.5 - 3.0 liters (depending on oil filter change)
Brake Fluid Type:
DOT 4 brake fluid
Fork Oil Type:
Motorcycle fork oil, SAE 7.5W or 10W recommended (check manual for specific viscosity and level)
Common Wear Items:
Clutch plates, output shaft seal leaks, rear main crankshaft seal (crank seal), carburetor float bowls, fuel line degradation, ignition coil failure, swingarm bearings, and fork stanchion wear.
Electrical Gremlins:
Wiring harness chafing, loose connections, and aging rectifier/regulator units can cause intermittent electrical faults.
Paralever Maintenance:
The Paralever driveshaft boot and universal joint require regular inspection and lubrication to prevent premature wear.
Heritage:
BMW's motorcycle division has a long and distinguished history dating back to the early 20th century, known for engineering excellence and innovative designs.
Gs Development:
The GS (Gelände/Straße - Terrain/Street) line originated with the R80G/S in 1980, which established BMW's reputation in the dual-sport segment. The R80GS and R100GS were direct evolutions, with the R100GS introducing the Paralever rear suspension in 1987 for improved ground clearance and reduced drivetrain lash.
Production Period:
R80GS produced from 1987-1990. R100GS produced from 1987-1996. The R80GS Paris-Dakar models were special editions based on these platforms.
Manufacturing Location:
Berlin, Germany