| Attribute | Specification |
|---|---|
| Production Years | 1986 – 1992 |
| Engine Type | Air-cooled Boxer Twin, 2-valve |
| Engine Oil | SAE 20W-50 (API SF/SG Mineral) (2.5 L) |
| Front Tire | 90/90 – 18 51H |
| Rear Tire | 120/90 – 18 65H |
| Spark Plugs | Bosch W 7 DC / NGK BP6ES |
| Battery | 51913 (12V 19Ah) |
The BMW R 100 RS (0377) occupies a unique place in motorcycling history. While the original RS was the first mass-produced motorcycle to feature a wind-tunnel-developed full fairing, this specific 1986-1992 iteration represents the ‘Monolever’ era. Interestingly, BMW had intended to phase out the air-cooled Boxer in favor of the K-series ‘Flying Brick,’ but overwhelming demand from enthusiasts and dealers forced the factory to return the R 100 RS to production in 1986 with modernized chassis components.
Technical Engineering Overview
The 0377 variant is distinguished from its predecessor by the single-sided swingarm (Monolever) and the move to 18-inch wheels both front and rear. This change significantly improved handling stability and simplified rear wheel removal. The 980cc boxer engine, though slightly detuned compared to the 1970s versions to meet stricter noise and emission standards, remains a masterclass in linear torque delivery and long-distance reliability.
Maintenance Guide & Specifications
Lubrication System
The R 100 RS relies on a traditional mineral-based lubrication system. At MotoSpecsLab, we emphasize using SAE 20W-50 API SF or SG mineral oil. Modern synthetic oils with high detergent levels can sometimes be too ‘thin’ for the tolerances of these older seals and gaskets. The system requires exactly 2.5 liters for a standard oil and filter change.
Chassis and Tires
The transition to 18-inch wheels requires specific tire sizing to maintain the intended geometry. For solo riding, maintain 2.2 bar (31.9 psi) in the front and 2.5 bar (36.2 psi) in the rear. When fully loaded with panniers and a passenger, these should be increased to 2.5 bar and 2.9 bar respectively to prevent sidewall overheating.
Electrical & Ignition
Reliable combustion is handled by either Bosch W 7 DC or NGK BP6ES plugs. Gapping should be checked every 5,000 miles. The electrical system is supported by a 51913 battery, which provides the necessary cold cranking amps to turn over the high-compression boxer pistons.
Expert Verdict
The BMW R 100 RS (0377) is the thinking rider’s classic. It offers the iconic aesthetics of the Hans Muth-designed fairing with the improved mechanical reliability of the late-series Monolever chassis. Provided the valve clearances are checked regularly and the Bing carburetors remain synchronized, this machine is capable of transcontinental journeys even decades after leaving the Berlin factory.