MARLBOROUGH MUSCLE CARS & BIKES MUSEUM
1982 Triumph T140 TSS
The last motorcycle model made by Triumph at their Meriden factory, the high performance T140W TSS was designed to appeal to the US market. The T140W 750cc was launched in 1982 and featured eight valve Weslake Engineering cylinder head hence the W suffix.
Triumphs had always suffered vibration problems and the source of much vibration from the parallel twin had been traced to flex in the crankshaft. A new crank was designed, a fully machined single forging with increased big end diameter making it much stiffer and better-balanced and producing one of the smoothest running motorcycles in the Triumph range.
At the heart of the T140W TSS performance boost is the Weslake-made cylinder head. Four valves per cylinder allowed for better gas flow and a more efficient combustion chamber design. In the old style head, the size of the two big valves meant the combustion chamber had to be hemispherical with the spark plug set to one side. To bring compression up to an efficient level, pistons had to have a domed top.
Four valves change the whole set-up; enabling valve angles to be more upright, the spark plug centrally placed and the chamber less domed. A new piston design with a flat top and cut-aways for valve clearance resulted in a piston lighter than before that allowed a 10:1 compression ratio. Moving the plug has a big effect - the flame path after ignition was shorter and more efficient.
Other changes from the standard T140 included beefed-up offset conrods, steel-liner alloy barrels, a strengthened swinging arm, a high output three-phase alternator, an Italian-made 4 gallon gas tank, twin front disc brakes and Marzocchi Strada rear shock absorbers.
Speed wise the T140W had a top speed of 120mph, ten more than a standard T140 Bonneville. Power wise the new T140W engine developed 58bhp, ten more than that of a standard T140 Bonneville. Performance wise the T140W TSS covered the quarter mile in 12.94 seconds at a terminal speed of 102mph compared with 14.4 seconds at 91mph for the T140 Bonneville.
When the Triumph factory at Meriden went into liquidation on 26 August 1983 it is estimated around 440 TSS bikes were built in total.
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