1978–1996 BMW R 80 GS / R 100 R Repair Manual (P/N C4085-91017)

• 168-page PDF containing the BMW Motorrad GmbH + Co., Service Department publication titled Repair Manual R 80 GS – R 100 R
• Factory tables identify R 80 GS, R 100 GS/PD, and R 100 R, with separate procedures for 1988 and 1991/Mod.91 versions, Paris-Dakar equipment, and R 100 R-specific components
• Maintenance schedules cover the 1,000 km inspection, 7,500 km inspection, 15,000 km service, and later 15,000 km service intervals
• Repair coverage runs from carburetor and ignition setup through brakes, forks, rear-wheel drive, gearbox, clutch, engine overhaul, and technical data

Maintenance and Technical Overview

The BMW workshop manual follows the shop sequence: pre-delivery checks, maintenance and inspection, operating materials, electrics, brakes, suspension, frame attachments, exhaust, gearbox, clutch, engine, and technical data. Maintenance coverage includes cylinder-head nut retorque, rocker-arm end play, valve clearance, compression testing, spark plugs, air filter and fuel-cock service, clutch play, static and dynamic ignition timing, carburetor synchronization with and without CO measurement, fluid changes, brake bleeding, wheel and steering-bearing checks, swing-arm play, and battery service.

Electrical repair work is centered on component testing and fault finding. Procedures cover alternator/regulator and diode-plate checks, starter tests with voltmeter and ammeter, ignition-coil resistance, relays, ignition trigger service, carbon brushes, and ignition, alternator, and starter troubleshooting flowcharts. Headlamp and instrument procedures are separated for Paris-Dakar, 1991-model, and R 100 R hardware where required.

Factory Repair Procedures and Tools

Engine coverage includes carburetor disassembly and setup, the USA SHED fuel system, engine removal, cylinder-head and valve repair, valve-guide and valve-seat inspection, piston/cylinder and connecting-rod measurement, oil-pump service, crankshaft and camshaft work, main-bearing checks, timing-chain service, and oil-cooler repair.

The gearbox chapter covers removal, shaft and bearing disassembly, kick-start components, seals, shift mechanism, shaft end-play measurement, spacer-ring calculation, assembly, installation, and troubleshooting. Rear-wheel-drive work includes pinion and crown-wheel bearings, taper-roller preload, backlash, shimming, tooth-contact pattern checking, and swing-arm bearings. Brake sections include front-caliper and master-cylinder repair, rear brake service, hydraulic lines, and bleeding. Suspension work covers GS and R 100 R fork teardown, stanchion/fork-bridge checks, steering-head bearings, wheel bearings, spoke and rim work, static balancing, track alignment, and rear spring-strut repair.

BMW special-tool references include internal extractor 00 8 573 with counter-support 00 8 570 for wheel bearings, measuring plate 23 3 650 with depth gauge 00 2 550 for gearbox shaft end play, and pin wrench 33 1 700 for rear-drive service.

Representative charts and diagrams include BMW Maintenance and Inspection Schedule – Engine and Transmission, BMW Maintenance and Inspection Schedule – Running Gear, Troubleshooting Ignition System, System Diagram of SHED Fuel System (USA), Checking Tooth Contact Pattern, and Report for Measuring Crankshaft Main Bearing Play. The electrical section is component-test and fault-finding focused; this edition does not contain a separate full wiring-diagram chapter.

Engine and Chassis Specifications

The technical-data section separates R 80 GS, R 100 GS/PD, and R 100 R values rather than applying one specification to all models. Cylinder-head nuts use a three-stage 15/25/35 Nm sequence, and rear wheel bolts are 105 Nm. Normal cold valve clearance at 20°C is 0.10 mm intake and 0.20 mm exhaust; 0.15/0.25 mm applies specifically during running-in up to 1,000 km. Gearbox oil capacity is 0.8 L, rear-wheel-drive capacity is 0.26 L, and the front hydraulic brake uses DOT 4 fluid. Engine oil with filter is 2.25 L for the earlier GS specification and 2.5 L for Mod.91/R 100 R.

Chassis tables show real configuration differences: rear spring travel is 180 mm on the GS models versus 135 mm on the R 100 R, while maximum permissible track misalignment is 5 mm for the GS and 10 mm for the R 100 R. Tire and rim sizes, fork dimensions and oil quantities, final-drive ratios, electrical values, bearing fits, wear limits, and tightening torques are also tabulated.

Several workshop cautions are specific to these repair procedures. The front-wheel bearing section requires the brake disc to be removed before the hub is heated to about 100°C; leaving it fitted can expose the disc to damaging heat distortion. During rear-drive setup, tooth contact must never run at the small-diameter end of the pinion, since incorrect shimming can concentrate load on the gear pair. The input-pinion procedure also warns against damaging the shaft sealing ring during nut installation, which can create an oil leak after assembly.

This BMW publication is written for standard-production motorcycles and machines fitted with Original BMW Accessories, not otherwise modified. It provides no serial-number/VIN range table; applicability is handled through model designation and change points such as 1988 and Mod.91. BMW also notes that later repair instructions may be issued through Service Information. Brake hydraulics, heated hubs and housings, compressed fork springs, and engine/transmission removal require the workshop support and safety precautions specified in the manual.