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BSA THUNDERBOLT 1964 Parts & Accessories

Founded in 1861 by a group of gunsmiths (the Birmingham Small Arms Trade Association) to manufacture armaments, BSA (Birmingham Small Arms Company) diversified into bicycles in 1880 and produced its first motorized motorcycle in 1903. By the 1950s, BSA had acquired Triumph Motorcycles and grown into the largest motorcycle manufacturer in the world, responsible for one out of every four motorcycles sold globally at its peak. Known for building reliable, utilitarian commuters alongside high-performance sporting singles and twins, BSA collapsed during the British motorcycle industry crisis of the early 1970s. The brand was acquired by India's Mahindra Group (via Classic Legends) in 2016 and revived with modern, retro-styled liquid-cooled models.

BSA categorized its models using single-letter family prefixes paired with engine capacity and functional role designations:

• B-Series & C-Series: Single-cylinder models (lightweight commuters to high-performance clubman racers)
• D-Series (Bantam): Lightweight two-stroke commuter models derived from wartime German DKW designs
• M-Series: Heavy-duty, side-valve single-cylinder workhorses and military utility machines
• A-Series: Parallel-twin engines spanning pre-unit and unit-construction architectures
• Rocket / Gold Star: Flagship performance designations reserved for high-output sporting and racing models

• Bantam Series (D1 to B175, 1948–1971): BSA's most successful model line, a lightweight two-stroke single (125 cc to 175 cc) based on the German DKW RT 125 design. Over 400,000 units were produced for Post Office workers, commuters, and learners.
• Gold Star Series (M24, B32, B34, DBD34, 1938–1963): Famous 350 cc and 500 cc hand-assembled single-cylinder sports machines named after Wal Handley's 100 mph lap at Brooklands. Dominated clubman racing, dirt track, and the Isle of Man TT in the 1950s.
• M20 / M21 (1937–1955): Heavy-duty 500 cc and 600 cc side-valve singles known for extreme reliability. The M20 served as the primary motorcycle of the British Armed Forces during WWII, with over 126,000 units supplied.
• B25 / B44 / B50 Unit Singles (1960s–1970s): High-compression single-cylinder roadsters and dual-sports (250 cc to 500 cc), including the B44 Victor (developed from Jeff Smith's World Motocross Championship-winning bikes) and the late-era B50 Gold Star.

• A7 & A10 Pre-Unit Twins (1946–1962): BSA's first major post-war parallel-twin line. Included the 500 cc A7 (Shooting Star) and 650 cc A10 (Golden Flash, Super Rocket, and the rare Rocket Gold Star).
• A50 & A65 Unit Construction Twins (1962–1972): Integrated engine/gearbox ("unit") parallel twins. Encompassed the 500 cc A50 Royal Star and 650 cc A65 models (Thunderbolt single-carburetor roadster, Lightning dual-carburetor sport bike, Spitfire high-performance model, and Firebird Scrambler).
• Rocket 3 / A75 (1968–1972): BSA's flagship 750 cc pushrod triple-cylinder motorcycle (developed alongside the Triumph Trident T150). Featured forward-inclined cylinders and distinct styling, standing as one of the final models built before BSA's collapse.

• Gold Star 650 (2022–Present): Neo-retro roadster featuring a liquid-cooled 652 cc single-cylinder engine (45 HP) wrapped in classic 1950s DBD34 styling cues.
• Bantam & Scrambler 650 Concepts/Variants: Modernized middleweight dual-sport and scrambler iterations built around the updated liquid-cooled 650 platform.