
BMW R51
Key specifications
Overview
### The Timeless Charm of the 1940 BMW R51 In the annals of motorcycle history, few machines capture the essence of post-war engineering and style as beautifully as the 1940 BMW R51. This allround motorcycle epitomizes the German maker's dedication to quality, performance, and innovative design. Positioned as a versatile option for both city commuting and long-distance touring, the R51 showcases BMW's prowess in crafting motorcycles that are not only functional but also imbued with a sense of timeless elegance. With its classic lines and robust construction, the R51 remains a sought-after gem for collectors and enthusiasts alike. At the heart of the R51 lies a potent 494cc two-cylinder boxer engine, which represents a hallmark of BMW's engineering expertise. Producing 24.07 horsepower at a modest 5600 RPM, this four-stroke powerplant delivers a satisfying blend of power and efficiency. Riders can expect a top speed of 140 km/h (87 mph), making it a capable companion on both winding roads and open highways. The engine’s 6.7:1 compression ratio and balanced bore and stroke dimensions (68mm x 68mm) contribute to its smooth performance, while the Amal carburettor ensures precise fuel delivery. The four-speed gearbox, combined with a reliable shaft drive, offers seamless power transfer, enhancing the riding experience with added confidence and control. The R51 is not just about power; it also incorporates advanced features for its time that enhance comfort and safety. The motorcycle is built on a sturdy steel single cradle frame that supports a sophisticated suspension system featuring cartridge front suspension and a twin-shock swingarm at the rear. The 200mm drum brakes at both ends provide reliable stopping power, while the 14-liter fuel tank allows for extended journeys without frequent refueling stops. Visually, the R51’s design is both functional and aesthetically pleasing, ensuring that it stands out on the road. With a weight of 182 kg (401.2 lbs), it strikes a balance between being lightweight for agility and robust for stability. ####
Pros
Cons
- Iconic Design: The R51's classic styling and attention to detail make it a timeless collectible, appealing to enthusiasts and casual riders alike.
- Smooth Engine Performance: The boxer engine provides a unique riding experience with excellent low-end torque and a satisfying power delivery.
- Comfortable Ride: The combination of a well-engineered suspension system and a comfortable seating position makes it suitable for both short commutes and longer journeys.
- Limited Top Speed: While 87 mph is respectable, it may not satisfy those looking for high-speed performance or modern highway capabilities.
- Drum Brakes: The use of drum brakes, while effective for the time, may not offer the stopping power and responsiveness that contemporary riders expect.
- Kick Start Only: The traditional kick start may deter some modern riders who prefer the convenience of electric starting systems found in today's motorcycles.
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)
- 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)