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

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 1939 BMW R51: A Timeless Classic on Two Wheels The 1939 BMW R51 stands as a testament to the brand's commitment to engineering excellence and innovative design during a pivotal era in motorcycle history. Positioned in the allround category, the R51 was crafted for riders seeking a balance of performance, reliability, and comfort. This model represents a significant leap forward for BMW, showcasing their mastery of the iconic boxer engine layout and establishing a legacy that enthusiasts still cherish today. With its elegant lines and robust design, the R51 remains a sought-after classic, appealing to collectors and riders who appreciate the rich heritage of German engineering. At the heart of the R51 lies a sophisticated two-cylinder boxer engine, displacing 494cc and delivering a robust 24.07 horsepower at 5600 RPM. This four-stroke powerhouse is configured with a 6.7:1 compression ratio, allowing for spirited acceleration and a top speed of 140 km/h (87 mph). Riders will appreciate the smooth power delivery and the distinctive thrum of the boxer engine, which provides a unique riding experience that’s both engaging and memorable. The R51's 4-speed gearbox and shaft drive contribute to its effortless handling, making it a superb choice for both leisurely rides and spirited outings. The R51 is not just about power; it incorporates features that elevate the riding experience. Its steel single-cradle frame ensures durability while maintaining a lightweight feel, complemented by a sophisticated cartridge front suspension and a twin-shock swingarm at the rear. Stopping power is delivered through dual 200 mm drum brakes, providing reliable performance even in challenging conditions. With a fuel capacity of 14 liters, riders can embark on longer journeys with confidence, knowing they have the range to explore the open road. The classic kick starter adds to the nostalgic charm, reflecting the era's simplicity and mechanical beauty. ###

Pros

    Cons

    • Iconic Boxer Engine: The unique two-cylinder boxer design offers a distinctive riding experience with a low center of gravity and smooth power delivery.
    • Timeless Aesthetics: The elegant styling and classic lines make the R51 a true head-turner, appealing to vintage motorcycle enthusiasts and collectors alike.
    • Comfortable Ride: The combination of robust suspension and ergonomic design ensures a comfortable ride for both the rider and passenger, making it ideal for longer journeys.
    • Limited Modern Features: As a classic motorcycle, it lacks some modern conveniences such as electric start and advanced braking technologies.
    • Maintenance Requirements: The vintage design may require more frequent maintenance and care, especially for parts that are no longer in production.
    • Performance Compared to Modern Bikes: While remarkable for its time, the R51’s performance may feel less powerful compared to contemporary motorcycles, which can dissuade some riders seeking high-performance capabilities.

    Technical details

    Source specification data

    Make
    BMW
    Model
    R51
    Category
    Allround
    Starter
    Kick
    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
    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)