Motorcycles were widely used by all major combatant nations during World War II, offering a lighter and faster alternative to traditional four-wheeled military vehicles. These two-wheeled machines primarily served in auxiliary roles, supporting rapid communication, reconnaissance, and liaison duties across various theaters of war. Although they lacked the armor and carrying capacity of trucks and jeeps, their speed and maneuverability were valuable for maintaining contact between front-line units and rear command. Military motorcycles were designed for durability and simplicity, adapting functional engineering for the harsh realities of global conflict.
Motorcycles of the Western Allies
The United States and the United Kingdom relied heavily on domestic manufacturers, prioritizing rugged and easily mass-produced models. Harley-Davidson was the most prolific American supplier with the WLA, often nicknamed the “Liberator” in Europe. Approximately 70,000 WLA and WLC (the Canadian variant) units were built during the war, along with 30,000 sets of spare parts.
The WLA was based on the civilian WL model, featuring a 45-cubic-inch (740 cc) side-valve V-twin engine. This engine was detuned for durability and used a low 5:1 compression ratio, allowing it to run reliably on low-octane field fuel. Military modifications included a heavy-duty luggage rack for radios, a rifle scabbard, and fenders with cut-away sides to prevent mud buildup.
Indian Motorcycle, the other major American manufacturer, contributed the Model 741. This model was based on the Junior Scout and featured a smaller 30.5-cubic-inch (500 cc) V-twin engine producing about 15 horsepower. Although less powerful than the Harley, approximately 35,000 units were produced, primarily for Allied nations like Great Britain and Russia.
Across the Atlantic, the British War Office standardized simple, reliable single-cylinder designs, primarily using the BSA M20 and the Matchless G3L. The BSA M20 proved to be one of the longest-serving models, with over 126,000 units produced, making it the most numerous single type of motorcycle in the war. It was powered by a simple 500 cc side-valve engine known for its low-end torque and ability to operate on poor-quality fuel. Modifications included a large Vokes air filter for desert operations.
The Matchless G3L was adopted in 1941 as a lightweight alternative; the “L” stood for “lightweight.” Its single-cylinder 350 cc engine produced about 16 horsepower. It was notable for being one of the first military motorcycles to feature “Teledraulic” telescopic front forks with oil damping, which provided a more capable ride than older girder fork designs. The G3L was popular for dispatch riders, with Matchless manufacturing around 80,000 G3 and G3/L models for the British Army.
Motorcycles of the Axis Powers
The German Wehrmacht and the Imperial Japanese Army often favored heavy-duty sidecar combinations for increased payload and off-road capability. German engineering produced two of the most technically sophisticated military motorcycles of the conflict: the BMW R75 and the Zündapp KS 750. Both machines were designed to meet stringent military specifications, including the ability to carry a 500 kg payload and maintain a minimum speed of 4 km/h to accompany marching troops.
The BMW R75 featured an integral two-wheel drive system, using a shaft to drive both the motorcycle’s rear wheel and the sidecar wheel, combined with a locking differential for maximum traction. Its 745 cc overhead-valve flat-twin engine was paired with a two-stage transmission offering road and off-road gear ratios, including reverse. This allowed the R75 to operate effectively in harsh environments like the Eastern Front and the North African desert. Approximately 16,510 units were built before Allied bombing halted production.
The Zündapp KS 750 was the R75’s main competitor, sharing advanced features like the driven sidecar wheel and a differential lock. Its 751 cc flat-twin engine cylinders were angled at 170 degrees to increase ground clearance. The Wehrmacht urged BMW and Zündapp to standardize parts, resulting in an agreement that the two models would share about 70% common components. Over 18,000 units of the KS 750 were produced. Like the R75, it was frequently equipped with an MG34 machine gun mounted on the sidecar, creating a mobile fighting platform.
In the Pacific theater, Imperial Japanese forces utilized the Rikuo Type 97, which had American origins. The Rikuo was a licensed copy of a Harley-Davidson VL-series motorcycle, with the license acquired in the 1930s. The Type 97 featured a 1,274 cc V-twin engine and was commonly deployed as a sidecar combination. It included a drive gear to the sidecar wheel, necessary for traversing the muddy soils of China and Manchuria. Around 18,000 of these machines were used for reconnaissance and transport roles.
Key Military Design Features
Successful military motorcycles shared several functional engineering characteristics to ensure they could withstand combat conditions, regardless of origin. Robust construction was a primary requirement, involving heavy-duty frames and components designed to absorb the shock of rough terrain. Engines were often detuned versions of civilian models, utilizing low-compression ratios—typically around 5:1—to reliably combust low-grade, standardized military fuel.
High ground clearance was a universal necessity, achieved through extended front forks on American models and creative engine placement on German sidecars. This ensured vehicles could traverse deep ruts and obstacles without becoming grounded. Ease of field maintenance was also a high priority, favoring simple, side-valve engine designs like the Harley-Davidson WLA and the British BSA M20, which could be serviced with minimal specialized tools.
All military motorcycles were fitted with specialized equipment. This included blackout lighting systems to comply with wartime regulations, and protective features like engine skid plates and canvas-covered metal grips and foot pegs, the latter used to conserve scarce rubber resources.