| Specification | Data |
|---|---|
| Model Range | 1986 – 1992 |
| Engine Oil | Mineral SAE 20W-50 (API SF, SG, or SH) (2.75 L) |
| Tires (Front) | 90/90 – 18 51H |
| Tires (Rear) | 120/90 – 18 65H |
| Tire Pressure | F: 2.2 bar (32 psi) / R: 2.5 bar (36 psi) |
| Battery Type | 52515 |
| Spark Plugs | Bosch W 7 DC / NGK BP6ES |
A significant engineering milestone for the air-cooled boxer series, the BMW R 100 RS (Einarmschwinge), or Monolever, represents the refined return of the legendary RS fairing. While the original RS debuted in 1976, this 1986–1992 iteration integrated the single-sided swingarm technology first pioneered on the R 80 G/S, drastically improving rear-end rigidity and simplifying maintenance tasks like wheel removal.
Technical Review: The Monolever Refinement
The ‘Einarmschwinge’ version of the R 100 RS was launched after a brief hiatus in the mid-80s when BMW initially planned to phase out the boxer in favor of the K-series. However, customer demand for the 980cc air-head forced a comeback. This generation features a 60 hp (44 kW) output, optimized for torque and rideability rather than outright top speed compared to the earlier 70 hp versions.
The Monolever chassis significantly altered the bike’s handling characteristics. By replacing the traditional twin-shock setup with a single shock absorber and a braced swingarm, BMW reduced unsprung weight and eliminated the ‘jacking’ effect common in shaft-driven motorcycles of the era. The 18-inch wheels both front and rear provide a balanced, stable platform for high-speed touring.
Maintenance Guide & Technical Specifications
Lubrication and Fluids
For the 980cc boxer engine, Mineral SAE 20W-50 remains the gold standard. Modern synthetic oils are often too thin for the tolerances of these air-cooled engines and can lead to increased consumption or seal leaks. The system requires 2.75 Liters for a full change including the filter.
Tires and Chassis
The Monolever RS uses a specific tire combination: a 90/90 – 18 front and a 120/90 – 18 rear. Maintaining the correct pressure is critical for the longevity of the final drive and the stability of the fairing at speed. We recommend 2.2 bar (32 psi) for the front and 2.5 bar (36 psi) for the rear under standard load conditions.
Ignition and Electrical
The electrical system is supported by a 52515 battery. For optimal combustion, the Bosch W 7 DC or NGK BP6ES spark plugs are recommended. These should be checked every 7,500 km to ensure the air/fuel mixture is burning efficiently, which is vital for preventing carbon buildup on the large 94mm pistons.
Expert Verdict
The R 100 RS Monolever is widely regarded by collectors as the most ‘practical’ of the classic RS line. It combines the iconic wind-tunnel-tested fairing with a more modern, reliable chassis. While it may lack the raw aggression of the early 70s models, its refinement makes it a superior long-distance tourer and a masterpiece of functional German engineering.