The 1955 BSA CB34 500cc Gold Star represents a pivotal moment in British motorcycle history, showcasing the transition to the ultimate development of Birmingham Small Arms' legendary single-cylinder racing platform. Renowned for its hand-built engineering and formidable clubman racing pedigree, this 499cc powerhouse was designed for riders demanding uncompromising performance on both the public roads and the Isle of Man tourist trophy circuits. The ‘55 represents the classic "big fin" era of post-war British motorsport excellence.

The bike before you was purchased by the current owner in 1971 in Austin, TX as an abandoned vehicle for the sum of $17.50. It is unrestored and remains the only bike he’s ever owned.

Historical Significance & Evolution

• The CB Transition: Introduced as a significant step in the Gold Star's evolution, the CB engine featured deeper, more square cooling fins and a shorter connecting rod compared to the earlier BB series, drastically improving thermal efficiency and high-RPM reliability.

• Clubman Dominance: The CB34 was born in an era where BSA utterly dominated clubman racing across the UK. It provided privateers with a machine that could be ridden to the track, raced to victory, and ridden home.

• Hand-Built Legacy: Every Gold Star engine was individually hand-assembled at the Small Heath factory and tested on a dynamometer. The motorcycle was delivered to its first owner only after its power output met strict factory performance standards.

Production Run

1954–1955 (The CB series had a focused, short-lived production window)

Engine Type

499cc air-cooled single-cylinder OHV four-stroke

Factory Test

Accompanied by official factory dynamometer test sheets

Market Status

Highly prized transitional model preceding the ultimate DBD34 series

Technical Specifications

Engine & Powertrain

• Engine Type: 499cc air-cooled, four-stroke, vertical single-cylinder (pushrod OHV)

• Cooling: Distinctive extra-large alloy cooling fins (popularly known as the "big fin" engine)

• Induction: Typically paired with high-performance Amal TT or GP carburetors

• Drivetrain: 4-speed manual gearbox available with optional close-ratio gear sets for racing

Chassis & Performance

• Suspension: Lightweight duplex steel frame equipped with telescopic front forks and swingarm rear suspension

• Braking System: Full-width internal expanding drum brakes for optimized stopping power

• Configuration: Highly customizable from the factory, built in road, clubman, scrambles, or trials trims

• Top Speed: 100+ mph (161 km/h)