After legendary Triumph boss Edward Turner retired from his motorcycle factory in 1963, he holed up in a BSA subsidiary, CarBodies Ltd of Coventry, but simply couldn’t keep his hand off his original passion, two wheels. Having entered the hallowed pantheon of Motorcycle Greats with his popular, stylish, and sometimes avant-garde machines from the 1920s onwards, he is best remembered as the man who made a parallel-twin engine look like a twin-exhaust-port single cylinder machine (the 500cc Speed Twin of 1938), which fit snugly into the existing ‘Tiger 90’ single-cylinder chassis. This new combination had magic in name, looks, and performance, and set the tone for the British motorcycle industry for the nearly 50 years.

The prototype Triumph DOHC twin as built in 1968; note the reverse-cone muffler (very similar to the first Tiger 100 ‘cocktail shakers’ of 1938), disc brake, and square tank styling, akin to the Ducati Monza [from Jeff Clew’s book, Edward Turner: the Man Behind the Motorcycles]
Edward Turner visited Japan in 1960, and was devastated to see firsthand the technical superiority of both the motorcycles and production methods of the Japanese industry, regardless the bikes built at that time were of small capacity (250cc and under), or clones of larger foreign machines (eg, the Kawasaki ‘W1’ copy of the BSA A10, and the Rikuo H-D clone). Turner came home to sound the alarm, but was unable to rouse his Board of Directors to make the necessary investment (during their years of greatest profitability, when they conceivably could have invested) to produce a modern motorcycle design in England.  Frustrated, Turner chose to retire, unhappy with the direction of the British industry as a whole. Still, he had always done interesting work as a freelancer, having come up with an advanced overhead-camshaft single-cylinder bike in 1925, and penned the foundation for what became the overhead-camshaft Ariel ‘Square Four’ in 1928 – which got him a job at Ariel under Valentine Page, and his radical design developed into metal by 1930.

A youthful Edward Turner, while still at Ariel Motors in the early 1930s.  A man of Olympian design talent, with a monumental ego to match! [Quarto]
From the sidelines in 1967, Turner sketched out a direct challenge to the Honda CB450 ‘Black Bomber’, whose performance nearly equaled his beloved but aging line of 650cc Triumph twins… the Honda rubbing salt in the wound with an electric starter and leak-free, reliable running. Turner poached a few Triumph employees to build up a running prototype of his double-overhead-camshaft, twin-cylinder 350cc bike with a short-stroke, 180degree crankshaft – exactly the spec of the Honda, but with 100cc less capacity. Turner was confident his decades of experience squeezing power from his twins would yield excellent performance from this smaller engine, and so it proved to be. The little bike hit 112mph in tests, about 7mph faster than the Honda. The styling was clearly inspired by the contemporary Ducati Monza, which wasn’t the first or last time the English took a leaf from the book of Italian bodywork.

Wesley Wall of the NMM staff tests the prototype [Chris Pearson]
While an advanced machine on paper, with a mechanical disc brake, those cams up top, and excellent performance, the reality was, Turner had designed a hand grenade. The Triumph brass, including new Triumph Chairman Eric Turner (no relation) instructed chief engineer Bert Hopwood to ready the experimental machine for production. Hopwood, performing an autopsy on the little machine after it broke its crankshaft on test, considered the design “fundamentally unsafe”, and set about, with Doug Hele, designing a wholly new motorcycle, with enough of the ‘ghost’ of Turner’s idea clearly visible to satisfy the Board.

The restored prototype of the Triumph Bandit, brought back to life by the National Motorcycle Museum [Chris Pearson]
Hopwood’s version of the DOHC twin, called the ‘Bandit’, had a stronger crankshaft, a chain primary drive instead of expensive gears, a 5-speed gearbox, electric starter, and a frame based on Percy Tait’s 500cc grand prix racer, designed by Ken Sprayson of Reynolds Tube. The Bandit was a real winner, with the same performance as Turner’s machine, but promised reliability, excellent handling, and truly modern specification. BSA shifted its mighty girth and tooled up for production in 1971, but less than 30 machines were built before the plug was pulled on the whole enterprise, as BSA declared bankruptcy, and the British motorcycle industry began a period of free fall.

The chain-driven camshaft drive can be clearly seen on the end of the crankshaft, as well as the shifter gate. [John Woodward]
Turner’s prototype has been restored to running condition by John Woodward, on staff at the National Motorcycle Museum in Birmingham. Many thanks to Mick Duckworth for forwarding these photos and information about the prototype!

Pull the pin, lad, and it’ll shortly explode…the original ‘hand grenade’ crankshaft of the Bandit. [John Woodward]
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