Back to Bike FinderYears: 1940 · 1939 · 1938
BMW R51
1938Allround

BMW R51

Key specifications

Engine
494 cc
Power
24 HP
Fuel type
petrol
Fuel capacity
3.7 L
Transmission
4-speed
Front brakes
Expanding brake (drum brake)
Rear brakes
Expanding brake (drum brake)

Overview

Introducing the 1938 BMW R51: A Classic All-Rounder The 1938 BMW R51 stands as a testament to the brand's pursuit of engineering excellence and innovation during the pre-war era. As an all-round motorcycle, the R51 was designed to cater to a variety of riding styles and preferences, making it a versatile companion for enthusiasts of the time. With its sleek lines and distinctive boxer engine layout, the R51 not only captures the aesthetic allure of classic motorcycles but also represents a pivotal moment in BMW's storied history, when the brand solidified its reputation for quality and performance. Engine Performance and Riding Characteristics At the heart of the R51 lies a robust 494cc two-cylinder boxer engine, delivering a commendable 24.07 horsepower at 5600 RPM. This four-stroke powerhouse, with its 6.7:1 compression ratio, provides riders with a smooth and reliable performance, achieving a top speed of 140 km/h (87 mph). The well-balanced design of the engine contributes to the motorcycle's remarkable stability, ensuring a confident and enjoyable ride whether you're navigating city streets or cruising along scenic country roads. With a 4-speed gearbox and a dry single-plate clutch, the R51 offers a responsive and engaging riding experience that resonates with enthusiasts seeking both power and precision. Key Features and Technology The R51 is equipped with a steel single cradle frame that not only enhances its durability but also contributes to its agility on the road. The motorcycle features drum brakes—both front and rear—measuring 200 mm in diameter, providing adequate stopping power for its time. The front suspension utilizes a cartridge system, while the rear suspension employs a twin shock swingarm configuration, ensuring a comfortable ride over uneven terrain. Coupled with a fuel capacity of 14 liters (3.70 gallons) and an impressive fuel consumption rate of 4.00 liters per 100 km (around 58.81 mpg), the R51 is designed for longer journeys, making it a practical choice for touring. Although it utilizes a kick starter, the simplicity of this feature complements the R51’s vintage charm, appealing to purists and collectors alike. **

Pros

    Cons

    • Timeless Design: The classic aesthetic and boxer engine layout capture the essence of vintage motorcycling.
    • Reliable Performance: The 494cc engine delivers smooth power and a solid riding experience, perfect for varied road conditions.
    • Fuel Efficiency: With a consumption rate of 4.00 liters/100 km, the R51 offers impressive mileage for long-distance rides.
    • Kick Start Only: The absence of an electric starter may deter some riders who prefer modern conveniences.
    • Limited Power: While adequate for its time, the 24.07 HP may not satisfy those seeking high-performance thrills in today’s riding landscape.
    • Weight Consideration: Weighing in at 182 kg (401.2 lbs), the R51 may feel a bit heavy for novice riders or those accustomed to lighter machines.

    Technical details

    Source specification data

    Make
    BMW
    Model
    R51
    Category
    Allround
    Starter
    Kick
    Carrying Capacity
    210kg
    Power
    24.07 HP (17.6 kW)) @ 5600 RPM
    Clutch
    Dry-single plate-cable operated
    Gearbox
    4-speed
    Ignition
    Battery
    Top Speed
    140.0 km/h (87.0 mph)
    Fuel System
    Carburettor. Amal
    Bore X Stroke
    68.0 x 68.0 mm (2.7 x 2.7 inches)
    Compression
    6.7:1
    Displacement
    494.00 ccm (30.14 cubic inches)
    Cooling System
    Air
    Engine Details
    Two cylinder boxer, four-stroke
    Fuel Consumption
    4.00 litres/100 km (25.0 km/l or 58.81 mpg)
    Greenhouse Gases
    O2
    g/km. (
    O2
    -
    Carbon
    dioxide emission)
    Lubrication System
    Wet sump
    Transmission Type Final Drive
    Shaft drive (cardan)
    Fuel Capacity
    14.00 litres (3.70 gallons)
    Overall Width
    815 mm (32.1 inches)
    Overall Height
    960 mm (37.8 inches)
    Overall Length
    2,130 mm (83.9 inches)
    Weight Incl Oil Gas Etc
    182.0 kg (401.2 pounds)
    Seat
    Single seat
    Rear Tyre
    3.50-19.00
    Frame Type
    Steel single cradle
    Front Tyre
    3.50-19.00
    Rear Brakes
    Expanding brake (drum brake)
    Front Brakes
    Expanding brake (drum brake)
    Rear Suspension
    Twin shock-Swingarm
    Front Suspension
    Cartridge
    Rear Brakes Diameter
    200 mm (7.9 inches)
    Front Brakes Diameter
    200 mm (7.9 inches)