R90S

1973 BMW R90S Technical Analysis & Specification Breakdown

Built around BMW's sport motorcycle platform, the 1973 BMW R90S utilizes a 898 cc (54.8 cu in) air-cooled two cylinder boxer, four-stroke layout. In factory specification, peak output is rated at 67.1 HP (48.9 kW) at 7,000 rpm while maximum torque reaches 76 Nm (56.1 lb-ft) at 5,500 rpm, transferring power to the rear wheel through shaft drive (cardan) final drive. With a specific output of 74.7 HP per liter and a 1,500 rpm working window between peak torque (5,500 rpm) and peak power (7,000 rpm), the engine character is indicating a tractable, stress-free state of tune focused on everyday usability and broad torque delivery.

On the scales, the R90S measures 215 kg (474 lbs) wet (curb), translating to a power-to-weight ratio of 0.31 HP/kg (3.2 kg per horsepower). Rider ergonomics and chassis geometry center around a 820 mm (32.3 in) seat height — resulting in a taller command-style riding posture suited to medium-to-tall inseams, combined with a 1,465 mm (57.7 in) wheelbase engineered for balanced agility and highway composure. The 24-liter (6.3 US gal) fuel tank supports practical everyday commuting and weekend road stints, while factory top speed is listed at 200 km/h (124 mph).