BSA M20 – 500cc – 1942


The BSA M20 500cc, produced in 1942, is a notable military motorcycle manufactured by Birmingham Small Arms Company (BSA), a prominent British motorcycle manufacturer. Here’s a comprehensive look at its specifications, manufacturer design, legacy, and interesting facts:


  • Engine: 496cc air-cooled single-cylinder, four-stroke engine.
  • Power: Approximately 13 horsepower.
  • Transmission: 4-speed gearbox.
  • Frame: Rigid frame with telescopic front forks and plunger rear suspension.
  • Brakes: Drum brakes (likely mechanical).

Manufacturer Design:

The BSA M20 was designed as a rugged and reliable motorcycle primarily for military use during World War II. It featured a robust frame and suspension setup suitable for rough terrain and adverse conditions. The design prioritized durability, ease of maintenance, and functionality over comfort and aesthetic considerations.


  1. Military Service: The BSA M20 was widely used by Allied forces during World War II, including by the British Army, for reconnaissance, dispatch, and general-purpose transport duties. Its reliability and durability earned it a reputation as a dependable military motorcycle.
  2. Popularity: Post-war, surplus BSA M20 motorcycles became popular among civilians due to their affordability and robustness. Many were converted for civilian use, contributing to BSA’s commercial success in the immediate post-war years.
  3. Longevity: The BSA M20 platform remained in production beyond World War II, undergoing various updates and modifications to meet changing military requirements and civilian demands.

Most Interesting Facts:

  1. Versatility: The M20’s design allowed for easy customization and adaptation, making it suitable for a wide range of military roles and later civilian applications.
  2. Reliability: The M20’s 500cc engine provided sufficient power for military tasks while maintaining reliability and ease of maintenance, essential qualities for military motorcycles of that era.
  3. Iconic Design: The M20’s rugged appearance and utilitarian design became iconic, embodying the essence of a classic military motorcycle from the mid-20th century.


The BSA M20 500cc holds significant historical importance as a military motorcycle that played a crucial role during World War II. Its legacy includes not only its wartime service but also its impact on post-war motorcycle production and civilian use. The M20’s robust design and reliable performance contributed to BSA’s reputation as a leading manufacturer of motorcycles during the mid-20th century.

In summary, the BSA M20 500cc remains a revered example of British motorcycle engineering, valued for its durability, versatility, and historical significance in both military and civilian contexts.


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