1948 Triumph Speed Twin
Claimed power: 28.5hp @ 6,000rpm
Top speed: 85mph (est.)
Engine: 498cc air-cooled OHV parallel twin, 63mm x 80mm bore and stroke, 6.5:1 compression ratio
Weight: 374lb (170kg)
Fuel capacity: 4.76gal (18ltr)
Price then/now: $450 (est.)/$7,500-$12,500
Only 49 miles show on the Smiths speedometer, but this all-original 1948 Triumph Speed Twin has traveled some hefty distances. Come again?
Before we get too far into the story, let’s chart the mileage. According to current owner and motorcycle collector Sid Chantland, this Speed Twin left Triumph’s factory in Meriden and went to Al Shirer’s Indian and British motorcycle shop in Allentown, Pennsylvania, a journey of 3,442 miles. When it left Allentown, the Speed Twin traveled to Japan, a journey of 6,710 miles. From Japan, the Triumph was shipped to Northern California, roughly 5,249 miles. Finally, it moved from California to Sid’s property near Minneapolis, Minnesota, another 2,076 miles.
The distances are approximate, of course, but that’s a grand total of 17,477 miles, all without the engine ever having been fired: The 49 miles accumulated while being rolled around during all those moves. As an essentially untouched Triumph Speed Twin, it’s an exceptional time capsule.
Beginnings of the twin
Triumph built an experimental 600cc side-valve vertical twin engine in 1913, but World War I disrupted further development. Unfortunately, not much is known about this early twin-cylinder powerplant.
Then, in the early 1930s, seminal motorcycle engineer and designer Val Page drew another twin for Triumph, which they dubbed the 6/1. It had a short life, being built only from 1934 to 1936. Page also designed a range of Triumph singles with 250, 350 and 500cc sidevalve and overhead valve configurations. None of these Triumphs were inexpensive to produce, and by the mid 1930s the company was facing financial
Jack Sangster owned the Ariel motorcycle company at this time, and had earlier employed designer Edward Turner at his factory. In Triumph’s travails, Sangster saw an opportunity to purchase the foundering company, and he moved designer Turner from Ariel to Triumph. Page had already left Triumph, taking his considerable design talents to rival maker BSA.
In 1936 at Triumph, Turner became chief designer and managing director. His first exercise was to take the three Page-designed overhead valve single-cylinder machines and dress them up with a sportier image. The result was the 250cc Tiger 70, 350cc Tiger 80 and 500cc Tiger 90, all with polished alloy primary cases, chrome plated gas tanks with silver-sheen painted side and top panels and purposeful looking high-level exhaust systems. The frames were rigid, and front suspension was supplied by a set of girder forks. These singles were popular sellers, but Turner had something else in mind for Triumph; an entirely new twin.
For his new engine, Turner drew a twin-cylinder with a vertically split crankcase housing a single, central flywheel. The 498cc engine featured a 63mm by 80mm bore and stroke, with its crankpins “in line” so both pistons rose and fell simultaneously. This means the cylinders fire alternately, with power impulses spaced evenly at 360 degrees.
Early Speed Twin engines are fitted with a six-stud cast iron barrel. The cylinder head is also of cast iron, with separate alloy boxes housing both the rockers and valve adjusters. Camshafts are situated high in the crankcase, gear driven through an idler gear by the right side of the crankshaft. Separate pushrod tubes run fore and aft of the cylinders, with ignition supplied by a Lucas twin magneto/dynamo mounted on a cast platform to the rear of the engine.
Turner dropped his parallel-twin engine into the heavyweight Tiger 90 single-cylinder cycle parts, which were painted Amaranth Red, and the 5T Speed Twin was born.
Triumph introduced the Speed Twin in July of 1937 at the Olympia Show in London, England. It was a sensation, and Turner’s compact twin-cylinder powerplant ultimately influenced Britain’s entire motorcycle industry. The major competition, including BSA, Norton, and Royal Enfield, all eventually produced their own parallel twin engines.
Upon its introduction, Turner’s twin-cylinder engine looked very similar to what would have been a conventional twin-port single-cylinder, without being much wider or heavier. The twin made only four more horsepower than Triumph’s 500cc single (28 horsepower compared to 24 horsepower). But the power delivery of the twin rivaled that of the single; it was much more refined, with better torque and pull from low speeds, plus it was easier to start.
In 1938 the Speed Twin model sold very well when it was finally available for public purchase, although there was some trouble with the original six-stud barrel to crankcase fixing configuration. An eight-stud pattern was introduced in 1939.
The frame, forks, fenders, toolbox, gas tank panels and oil tank were all red (Triumph’s Amaranth Red is a deep red with a hint of purple). A gas tank-mounted instrument panel held an amp gauge, headlamp switch, inspection lamp and oil pressure gauge. For 1938 and 1939 the panel was made of Bakelite, which cracked easily. It was replaced in 1940 with a stamped metal item.
Chrome wheel rims, a WM2 x 20-inch at the front and WM2 x 19-inch at the rear, had their centers lined in red, highlighted by a thin gold pinstripe on each side. The 8-inch Lucas headlamp shell was chrome plated.
There were very few changes between 1939 and 1940, with the exception of the addition of helper or check springs on either side of the girder fork. For 1940, the gas tank capacity increased to nearly five U.S. gallons, and a color option of black and chrome (rarely chosen) with ivory lining was offered.
After the war
Civilian production ceased in 1940 following England’s entry into World War II, resuming following the end of the war for the 1945 model year. Changes included automatic ignition control and hydraulically dampened telescopic front forks, and the front wheel was reduced in size to 19 inches.
Further changes included fitting a smaller 7-inch headlight, and separating the generator from the magneto. The generator moved to the front of the engine cases, and the magneto — now a BT-H — stayed at the rear. The powerplant was further tidied up as the external rocker box oil drain tubes were removed. Oil was now routed through drilled oil passages in the cylinder head and cylinder block.
From 1945 to 1947, Triumph did all it could to simply meet demand for the Speed Twin, and there weren’t many changes in specification through those post-War years.
According to Harry Woolridge, who wrote The Triumph Speed Twin and Thunderbird Bible, in 1948 there were no alterations to the engine. However, Woolridge wrote: “ … during the season year (1948), several changes took place to the motorcycle parts. Due to circumstances beyond the company’s control, these changes could not be introduced at the onset of the season, but were brought in as and when convenient.”
And that brings us to Sid Chantland’s low-mileage Speed Twin. Going by the engine number, his motorcycle was built towards the end of 1947 as a 1948 model. Because it’s early in the production run, Sid’s Triumph features the original-style rear fender. One of the 1948 changes Woolridge spoke of — introduced when convenient — was an updated rear fender. This was wider, and there were only two stays on each side as opposed to three, as seen on Sid’s machine. To gain access to the rear wheel, this new fender could be unbolted under the saddle, and the entire section lifted away. To accommodate the updated fender, the rear subframe was also altered.
Sid’s Speed Twin was fitted with the rigid rear hub as opposed to Triumph’s new Spring Wheel, or sprung hub. Designed by Turner in 1938, the sprung hub allowed the rear wheel a total of approximately two inches of up and down movement on the wheel spindle. It didn’t make its first appearance until 1946, and was finally available in 1948 as an extra charge option.
When a Speed Twin came equipped with the sprung hub from the factory, the gearbox was modified to accept an external speedometer drive. The drive would normally have been found on the right side of the rigid rear hub. However, with a sprung hub, the speedo cable was driven from the rear of the final drive sprocket.
Sid’s Triumph did come, however, with the updated gearshift lever. The update? A rubber cover to protect the rider’s boot or shoe. Also in 1948, Triumph updated the headlight with domed glass, and spark plug caps became standard equipment. Sid’s machine reflects these changes.
Triumph went on to update the Speed Twin over the years, including changing to alternator electrics in 1953 and adopting a sprung frame in 1955. The 5T Speed Twin ran until 1958, when it was replaced with the 5TA Speed Twin. The 5TA ran until 1966.
Sid’s Triumph was shipped from Meriden to Al Shirer’s shop in late 1947 or early 1948. Why it was never uncrated and sold is a mystery, but Shirer managed to squirrel the Triumph away. An article in the September 1979 issue of Motorcyclist about “eclectic collectors” includes a photograph of Shirer standing on the seat of a Maico scooter surrounded by a myriad of other machines and detritus. According to the article, Shirer had hoarded motorcycles away in numerous locations.
Ronald W. Krause of Emmaus, Pennsylvania, eventually acquired Shirer’s estate (Krause was one of the first Honda motorcycle dealers in the U.S.) and on Oct. 22, 1984, he held an auction to liquidate the machines. In 1984, Sid was serving overseas in Germany, but his dad, Bob, and brother Scott attended Krause’s auction.
“That was quite an auction,” Bob says as he recalled the event. “If it were held today it would be a food fight.” There were several Indians sold, plus a number of Harley-Davidsons, BSAs and Triumphs, including the Speed Twin. “I don’t clearly remember seeing Sid’s Speed Twin at that auction, but that’s where it came from before it went to Japan.”
Fast forward to June 2008, when Sid and Bob traveled to Monterey, California, for a motorcycle auction. “I must have walked past the Speed Twin 50 times,” Sid says, “but I ignored it because I thought it was just another restoration. Then I started reading about it in the auction catalog, and it stated it was brand new, and came from the Al Shirer collection. I got up to look at it, and sure enough, it was an all-original motorcycle.”
The Speed Twin crossed the block early in the day, and Sid won the bidding. “It’s 100 percent accurate,” he says. “It’s got the instructions about the battery under the battery lid, the original tool kit and the original tire pump. I think the rear tire has been changed, but that’s probably because the original would have gotten a flat spot from sitting in the crate all those years.
“It’s got oil in it, and it turns over, but I have no interest in riding it. I wouldn’t mind starting it up, but I don’t think I’d ride it.”
It’s an amazing piece of history, as most Speed Twins have been, at least by now, restored two or even three times. “What these bikes were really like originally sort of gets lost in translation,” Sid says. “For all of the miles this Speed Twin has traveled, it’s as close to perfect as could be.” MC
- 1 year of Motorcycle Classics magazine both print and digital – six premium issues full of exciting and evocative articles and photographs of the most brilliant, unusual and popular motorcycles ever made!
- Special discounted prices on books, t-shirts, and archive products in the Motorcycle Classics Store
- Online access to Motorcycle Classics content dating back to 2005
- Access to exclusive online content - restoration projects, rides & destinations, and gear reviews.