The Triumph T100

Under the Radar
By Richard Backus
September/October 2010

The Triumph T100.
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Triumph T100
Years produced:
 1959-1974
Claimed power: 41hp @ 7,200rpm (1968 T100R)
Top speed: 105mph (1968 T100R)
Engine type: 490cc air-cooled OHV parallel twin
Transmission: 4-speed
Weight: 371lb (wet)
MPG: 45-60 (est.)
Price then/now: $1,199 (1968)/$4,000-$10,000

The Triumph T100 story begins in 1957, with Triumph’s introduction of the 348cc 3TA (“A” for unit construction) “Twenty-One” model, Triumph’s first twin with the transmission built in unit with the engine. Moto-journalists noted that the drivetrain seemed overbuilt for a 350, and that the under-square 58.25mm x 65.5mm cylinder dimensions would allow for a larger displacement version with a bigger bore. They were right.

The unit 5TA Triumph Speed Twin of 1959 arrived with the same 65.5mm stroke as the 350 but with a 69mm bore for 490cc. The sportier Triumph Tiger 100A (T100S from 1961) version arrived the following year. In the U.S., the Triumph T100 was available in two forms: The T100S/R streetbike and the T100S/C, which was more focused toward off-road use. The C model was intended to celebrate Triumph’s success in enduro racing, especially its wins at the famous Jack Pine event, but at first it was little more than a T100S/R with knobby tires — although it did acquire a high-pipe siamesed exhaust around 1964.

Racing development
Though the Triumph 650 Bonneville was Triumph’s best seller in the 1960s, the 500cc T100 and its variants were far more important in motorcycle racing competition. Until 1969, bikes with overhead valves were restricted to 500cc in AMA-endorsed competition events, including the prestigious Daytona 200 mile race, which between 1955 and 1965 had pretty much become a Harley benefit race. But Triumph engineer Doug Hele’s dogged development work on the T100’s performance and handling earned back-to-back wins at Daytona in 1966 and 1967 with Buddy Elmore and Gary Nixon riding.

Not for the first time in motorcycling history, a win in a famous race prompted a new model name. For 1967, the T100R Daytona replaced the T100S/R, and featured a new cylinder head with larger intake valves, racing “Q” cams with radiused followers, dual 1-1/8-inch Amal carburetors and a revised frame/swingarm. The result was 41hp in a bike with a curb weight of just 371 pounds, 25 less than the Bonneville. The Triumph T100 C street scrambler joined it shortly after.

The Triumph T100 C used a single Amal for 38hp and was fitted with a pair of smaller mufflers mounted high on the bike’s left side, a small 5-3/4-inch headlight, no tachometer, and knobby tires — all of which said “desert sled.” Though undeniably purposeful looking, in stock form with its street-oriented suspension the T100 C didn’t really cut it in the truly rough stuff, but made a pleasant “dual-sport” rider.

Lightweight performer
By the standards of the day, T100s were acceptably quick, reliable and comfortable. Cycle magazine tested the new Triumph T100 R in 1967 and recorded a 14.9 second standing quarter at a shade under 90mph, concluding that it had close to the performance of a Bonneville yet could be “whipped around” like a lightweight. Even the electrics came in for praise. Cycle’s only concern was the 7-inch single-leading-shoe front brake, which was described only as “adequate.”

Cycle World, meanwhile, discovered a “Jekyll and Hyde” personality: below 4,500rpm, the Daytona would work like “a strong 350”; but shifting instead at 6,000rpm, they found a whole new level of performance, and a top speed of 105mph. They also praised the T100R’s gear-shifting, ease of starting, comfort and electrics — except for the feeble horn — and found the brakes “more than adequate.” The improved handling came in for specific mention and was attributed to increased diameter frame tubes and a new fork design.

Cycle magazine took a 1968 T100C onto their off-road test track, and after dealing with some uncharacteristic stiction in the fork, they found the high-piper would handle narrow bumpy trails and deep sand equally handily, although the tester noted that the handlebars fitted were too narrow for real enduro work. However, by shedding the battery, toolbox and other unnecessary items, the T100C’s street weight could be stripped from 350 pounds to a very respectable 290 pounds. The biggest complaint centered around the high pipes, which made access to the toolbox almost impossible and required any passenger to have “an asbestos left leg.”

Later version
1968 was also the year the Daytona got the new BSA group 8-inch twin-leading-shoe drum front brake, which addressed its most serious shortcoming. (Except for a handful of final production machines in February 1974, the Daytona never got a disc brake.) From 1968, the Daytona continued more-or-less unchanged through 1974, while the Triumph T100C acquired a wire mesh heat shield over the headers and mufflers, with production running into 1972. Fortunately, the T100 variants were spared the horrors of the 1971 Triumph oil-in-frame fiasco, continuing with the lug-and-braze frame and separate oil tank.

But in the early 1970s, the world of motorcycling looked completely different from the heady days of the T100R Daytona introduction. Once praised for its power and smoothness, the same motorcycle was condemned by Cycle in 1974 as a sluggish vibrator when compared with the same year’s Yamaha TX500. The Yamaha was faster, smoother, had five gears, a disc brake and electric start, with all these components “integrated, coordinated, paneled, modularized, self-contained and muted.” The Triumph, on the other hand, looked “like the drawing of a small boy learning things mechanical.”

Time had caught up with the T100, as well as with the BSA-Triumph group — but there is a postscript. In November 1972, Triumph introduced the TR5T Trophy Trail/Adventurer (see Motorcycle Classics, January/February 2010), essentially a T100C drivetrain mated to BSA B50 Victor oil-in-frame running gear, combining the bulletproof twin engine in up-to-date cycle parts. It’s now a sought-after rarity, and according to British motorcycle guru Frank Melling, “… one of the best bikes ever produced by the British motorcycle industry … if only it had arrived seven years earlier.” MC

Half-liter rivals to the Triumph T100 Twin
Suzuki T500 Titan

• 47hp @ 7,000rpm
• 492cc air-cooled piston-ported 2-stroke parallel twin
• 5-speed
• TLS drum brake front (disc front 1976)/SLS drum rear
• 408lb (dry)
• 30-40mpg
• Price now: $1,400-$3,000

In the case of the Suzuki T500 Titan, conventional wisdom said it was impossible to build an air-cooled 2-stroke twin of more than 350cc. The problem: how to prevent the engine seizing from expansion of the piston and cylinders through heat buildup. Modern metallurgy was the answer.

It wasn’t all plain sailing, though. Early T500s earned a reputation for excessive fuel consumption, pernicious vibration and unstable handling. These issues were mostly addressed by the time the MkIII arrived in 1970.

By 1974, with the speed stakes firmly in the grasp of the new Superbike generation, the T500 was marketed as a mild-mannered tourer at a very competitive price point. A disc brake finally arrived in 1976, along with a new designation: GT500.

Like Triumph’s T100, the rapid technological changes of the early 1970s simply left the Titan behind. Be that as it may, like the Honda CB450, Suzuki’s big twin makes for an affordable, reliable classic Japanese motorcycle today, highly regarded by current owners.

Honda CB450
• 43hp @ 8,500rpm
• 444cc air-cooled DOHC parallel twin
• 4-speed (5-speed from 1968)
• TLS drum brake front (disc brake front from 1968)/SLS drum rear
• 412lbs (wet, 1968)
• 40-45mpg
• Price now: $1,500-$6,000

The Honda CB450 was the first Japanese motorcycle to seriously challenge the Brit bikes’ supremacy in the “heavyweight” class. It would top 100mph and run the standing quarter in the low 15s — not as fast as a British 650, but certainly as fast as the 500s. Notice had been given.

While the T100 was essentially a 1937 design, the CB450 was bang up to date. Launched in 1965, it incorporated plenty of Honda’s race-tested engineering, and was solidly put together. It was also good looking, a modern oriental interpretation of a traditional British parallel twin.

But it wasn’t perfect. The suspension was too soft, vibration was an issue, and four gears were inadequate for the power characteristics of the engine. A fifth cog arrived in 1968 for the K1 Super Sport and the new CL street scrambler version, together with improved rear shocks and a restyled gas tank. The engine was enlarged to 498cc for the “new” CB500 in 1975, which soldiered on for one more year before production of Honda’s venerable twin finally ended.


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Post a comment below.

 

alan hughes
10/15/2010 12:30:23 PM
The original and true Tiger 100C, was a very limited production bike, 1953. It had twin Amals, sprung hub and all ally. engine. Road tested at 62 in 1st,92 in 2nd, 104 in 3rd. and 116 in top. ! down, 3 up.


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