| Parameter | Specification |
|---|---|
| Production Years | 1987 – 1995 |
| Engine Oil | SAE 20W-50 Mineral (2.5 L with filter) |
| Tires (F/R) | F: 90/90 – 18 / R: 120/90 – 18 |
| Tire Pressure (Solo) | F: 2.2 bar / R: 2.5 bar |
| Battery | 52515 (25Ah) / 53030 (30Ah) |
| Spark Plug Gap | 0.6 – 0.7 mm |
The BMW R 100 RT (Type 0446) holds a unique place in motorcycling history as the bike that refused to die. In the mid-1980s, BMW Motorrad intended to phase out the air-cooled Boxer engines in favor of the liquid-cooled K-series. However, fierce demand from the global touring community forced BMW to bring back the 1000cc Boxer in 1987. This “second generation” R 100 RT was modernized with the Monolever single-sided swingarm and 18-inch wheels, blending classic airhead soul with improved chassis stability.
Engineering Overview: The 0446 Evolution
Unlike its twin-shock predecessors, the 0446 model utilized the chassis architecture from the R 80 series. The 980cc engine was detuned slightly from earlier high-output versions to meet stricter noise and emission standards, but it gained significant mid-range torque, making it a superior long-distance tourer. The iconic full fairing remained the industry benchmark for weather protection, utilizing a multi-piece design that effectively managed engine heat and wind buffeting.
Maintenance & Fluid Specifications
To maintain the longevity of the air-cooled Boxer, adherence to fluid intervals is critical. At MotoSpecsLab, we recommend the following technical standards:
- Engine Lubrication: Use a high-quality SAE 20W-50 Mineral oil. The Boxer design relies on oil for both lubrication and cooling; mineral oils are preferred for proper seal swelling and heat dissipation in these vintage tolerances. Capacity is 2.5 liters when replacing the filter.
- Ignition System: Optimal combustion is achieved using Bosch W7DC or NGK BP6ES plugs. Ensure the gap is precisely 0.6–0.7 mm to prevent strain on the electronic ignition modules.
- Electrical: The R 100 RT is a heavy-draw machine due to its touring accessories. It supports batteries ranging from 25Ah (52515) to 30Ah (53030). We recommend the 30Ah variant for riders using auxiliary lights or heated gear.
Tires and Handling
The shift to 18-inch wheels front and rear significantly sharpened the handling compared to the older 19-inch setups. For optimal safety and tire wear, maintain pressures at 2.2 bar (32 psi) in the front and 2.5 bar (36 psi) in the rear for solo riding. If carrying a passenger and luggage, the rear should be increased to 2.7 bar (39 psi).
Technical FAQ
Q: Why use mineral oil instead of synthetic?
A: Older Boxer engines feature tolerances and seal materials (such as pushrod tube seals) that were designed for mineral-based lubricants. Synthetics can sometimes lead to increased oil consumption or weeping in these specific 0446 units.
Q: What is the benefit of the Monolever over the earlier Twin-shock?
A: The Monolever system is 15% more torsionally rigid and simplifies rear wheel removal, which is a major advantage for roadside maintenance during long tours.