Well before WWII a talented engineer and designer unleashed a truly new motorcycle on the two-wheeled world. With only two cylinders and 26 horsepower, it might seem pretty damn tame by today’s standards. In 1937, however, a light and nimble motorcycle with as much or more power as many V-Twins was a big deal.
When Edward Turner came to work at Triumph, his task was to modernized the line, which consisted of single-cylinder machines that might best be characterized by two words – durable, but boring. Additional chrome and bright paint made the old models look, if not new, at least fresh. Luckily, Turner didn’t stop there.
Before coming to Triumph, Turner worked for Arial, where he developed the Square Four. Though the big Arial was never a top seller, it contained the seeds of a truly modern motorcycle, one that would ensure Triumph’s success for over forty years and share its DNA throughout the motorcycle world right into the next century.
The 500cc Speed Twin was in essence, half of a Square Four. With a 360-degree crankshaft, both pistons moved up and down in unison, but on opposite strokes. One was exhausting while the other was compressing. The cases were made of aluminum, though the cylinders were cast as one piece of cast iron. Ed must have been looking ahead when he specified the dimensions for the cylinders, because he left plenty of extra meat – just in case a 500cc motor wasn’t quite big enough. Like the cylinders, the heads were cast in iron as one piece. Located right behind the vertical twin was the transmission, a four-speed gearset housed in an Aluminum housing.
Triumph was able to bring the new model to market in a relatively short time for a number of reasons. One, Turner was able to borrow from what he learned at Ariel in developing the new engine.
Second, rather than develop a new frame along with all the necessary hardware and sheet metal, Ed Turner simply adapted the new twin to a frame meant for one of Triumph’s big singles. Presto, one very sexy vertical twin.
Triumph’s new engine wasn’t the first vertical twin. But, like Henry Ford’s V-8, it was the first successful vertical twin produced in big numbers. It was also the one that laid the foundation for a long list of vertical twins produced by a long list of motorcycle manufacturers.
In 1939 Triumph introduced the first offspring of the Speed Twin. With more compression and a ported head, the Tiger 100 would pull an easy 100 miles per hour – thus the name. A silver paint job with tasteful pinstripes helped Triumph separate their new hot rod from the more mundane Speed Twin with the Amaranth Red paint.
When war broke out in Europe it didn’t just slow down development at Triumph – it stopped all activity completely when a German bomb landed directly on the Coventry plant in November of 1940. Fortunately no one at Triumph was killed, and by 1942 they were able to begin production of a 350cc single meant for use by the army, in a new manufacturing plant.
By the time the war came to a close England was nearly bankrupt. The order from on top to English industry was simple – export. It just so happened that there were thousands of young American men freshly returned from serving in Europe, who were familiar with English vehicles and motorcycles in particular.
The US did indeed prove to be a fertile market for the sale of Triumphs and there was only one problem. Being Yanks, the young men buying the bikes believed in the old all-American adage: “there’s no substitute for cubic inches.” The Thunderbird, introduced in 1950, was the answer to their plea, and Triumph’s first 650cc production bike. Enlarging the bore from the stock 63 to 71mm wasn’t quite enough. By stroking the crank an additional 2mm, however, Triumph as able to create the new 650cc powerhouse.
The T-Bird came to market with a single, though larger, Amal carb, modest compression and a mild state of tune. It may not have been the true hot rod that American youngsters were looking for, but it was definitely faster than the 500, and it had the extra torque that comes with more cubes.
The T100 was the first offspring of the Speed Twin, and the T-Bird was the second. That pattern never stopped until Triumph did. Next came the T110, the highway hauler of the day. With more compression, ported heads, more aggressive cams, and another boost in the size of the single carb, the T110 came to market with 42 horses – and rear suspension to boot
Anyone familiar with vintage Triumphs knows that Turner and crew turned out off-road bikes as well as the better-known highway rides. The best known was the TR6, a 650 scrambler introduced in 1956. Not surprisingly, the TR6 morphed out of the TR5, a popular and fast 500cc off road Triumph. Once again, the Americans who bought the TR5 had only one suggestion – more cubic inches. Another birth was in the works. This time the boys across the pond slipped the 650cc engine from the T110 into a TR5 frame.
At this point in time, twin carbs were only found on the Daytona, Triumph’s hot rod 500cc machine. There was also a factory twin carb kit offered for the 650 bikes, but none of the 650s on the showroom floor came with two mixers.
Though it didn’t come with two carbs, the new TR6 turned out to be a very popular go-anywhere motorcycle. Some people saw the TR6 as a hot rod street bike, one without the full fenders and headlight nacelle seen on Thunderbirds and T110s. Off-road racers found the TR6 to be an excellent competition machine, whether raced in the desert or on the TT track.
The 1950s were good years for Triumph, and it seemed they won wherever they raced – including Bonneville. In 1956 Johnny Allen broke the land speed record when he ran 214 miles per hour in the Texas Cee-gar, a streamliner built by privateers and powered by one, naturally aspirated, Triumph 650cc engine.
Thus, when it came to picking a name for a new model, Triumph’s success on the salt flats proved the catalyst. Thus, as we all know, the new bike was named the Bonneville and it did indeed come to market with two carburetors.
The first-year Bonnie came to town with what you might call a suit and tie, the valanced fenders and headlight nacelle used throughout the ‘50s on the T Bird and T110. Though the first-year Bonneville is now a very collectible bike, in 1959 a lot of young men bought a TR6 instead of the Bonneville, and installed the twin-carb kit available from Triumph.
The sales of the Bonneville were so poor that the Triumph team was forced to re-think the bike. Luckily for us, instead of simply cancelling the Bonneville they kept the drivetrain and switched the sheet metal. From 1960 on the Bonneville looked like a proper American hot rod on two wheels. The headlight stood alone and proud, minus the nacelle. Gone were the fat English fenders. In essence, they took the Bonneville’s new look from the TR6.
From 1960 to 1970 the Bonneville evolved, with more power and better paint year by year. Throughout the decade the Bonneville’s reason for existence never really changed – a street brawler it remained. At that time there were two bikes to have on the street. One was the Harley-Davidson Sportster, and the other was the Triumph Bonneville – a bike made possible by an innovative design introduced 40 years before the first Bonneville arrived on this side of the Atlantic.
When the last of Ed Turner’s vertical twins rolled out of the plant is a matter of debate. In 1971 the big twins came in for a complete redesign, including a new oil-bearing frame. That decade saw the 650cc bikes grow to 750, the four-speed transmission move to five, and the front drum brake disappear, replaced by a disc. In spite of the apparent improvements, Triumph was slowly falling apart due to massive mistakes by management and nearly endless worker strikes. The end came in 1983 when the last bike rolled out the door.
The good news: As I write this story, the new Triumph Company (re-born by a new owner) is turning out thousands of Bonnevilles, Thruxtons and Bobbers, all powered by vertical twins. The new twins are intentionally designed to resemble the 650s of that special era. Thus it’s fair to say that these new counter-balanced and fuel injected twins do indeed owe their existence to Ed Turner and that very simple and clever design of 1937.
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