The Duzmo Model XX holds a special, if often overlooked, place in the tapestry of British motorcycling. Built in the early 1920s by the short-lived Duzmo Motor Cycle Company of Tottenham, London, it reflected the ambition of Jock Porter, a talented engineer, tuner, and later the 1922 Isle of Man TT Lightweight winner. The Model XX was Duzmo’s flagship design and the machine that best embodied Porter’s determination to bring lightweight performance motorcycles to serious enthusiasts.
Origins and History
After the First World War, Britain saw a boom in motorcycle production. Dozens of small firms sprang up, each seeking to offer affordable, lightweight transport or to carve a niche in the sporting market. Jock Porter, an energetic engineer with a flair for innovation, founded Duzmo in 1919. His approach was different: he wanted motorcycles that were not just utility machines but also carried a sporting edge.
The Model XX was developed to showcase this philosophy. Positioned as a “clubman’s” motorcycle, it promised speed and agility while keeping costs reasonable. Though Duzmo never had the financial backing of larger firms like BSA, Triumph, or Matchless, its designs caught attention among performance-minded riders.
Technical Design and Specifications
The Model XX was a compact yet purposeful machine, typically using JAP (J.A. Prestwich) single-cylinder engines—renowned for their durability and racing pedigree. Depending on customer order and availability, different specifications could be fitted.
- Engine: 348cc–499cc single-cylinder JAP, air-cooled
- Valve Configuration: OHV (overhead valve) on higher-performance versions; side-valve for roadster trims
- Carburetion: Amal or Brown & Barlow carburetors (period correct)
- Gearbox: Sturmey-Archer 2- or 3-speed manual, hand-change lever
- Frame: Lightweight tubular steel, rigid rear, girder front forks
- Brakes: Early drum or band brakes (front and rear), modest but sufficient for the time
- Top Speed: 55–65 mph depending on engine spec
- Weight: Approx. 220–250 lbs, giving an excellent power-to-weight ratio
The Model XX’s hallmark was its light frame and sporting geometry, which made it responsive in the hands of experienced riders. Combined with the lively JAP engines, it offered spirited acceleration and was well suited for competition in hill climbs and local speed events.
Market and Rider Impression
For clubmen and sporting riders of the early 1920s, the Model XX provided a refreshing alternative to heavier and slower utility machines. Its appeal was strongest with those who valued individuality and performance over mass-market reliability.
However, limited production numbers and Duzmo’s financial instability restricted its reach. The bikes were relatively costly for a small-brand machine, and buyers often leaned toward established names. Despite this, among those who rode them, the Model XX earned a reputation for its agility and racing potential.
Racing Connection and Legacy
Jock Porter himself used Duzmo machines as platforms to refine his racing expertise. His victories, particularly in the 1922 Lightweight TT on a New Imperial, were influenced by the knowledge he honed while working with the Model XX and other Duzmo machines.
While Duzmo ceased production in the early 1920s, the Model XX lives on as an important link in Britain’s early motorcycle racing culture. It represents the spirit of the “specialist builder”—small shops pushing boundaries with limited resources but immense passion.
Collectability and Vintage Status
Today, surviving Duzmo Model XX motorcycles are exceedingly rare. Many were lost to time due to the company’s short lifespan and the modest number of units built. When an example surfaces, it becomes a star attraction at classic motorcycle gatherings, admired not only for its scarcity but also for its story of independence and ambition.
For collectors, the Model XX is more than a machine—it’s a piece of British motorcycling folklore, representing a forgotten pioneer who helped shape the sport and engineering ethos of the 1920s.
