THE T100C TRIUMPH TROPHY 500CC TWIN
SMALLER IS BETTER SOMETIMES
By Matt Cuddy
One of the all time favorite dual purpose bikes was the 500cc Triumph Trophy Scrambler, designation T100C. Looking every bit like a scaled-down 650 twin, the 500cc bike shared few parts with the larger machines, and was aimed at the new rider. This is the unitized version (transmission and crankcase in one unit) vs. the pre-unit T100 that came out in 1956.
1967 T100C with megaphone pipes
The unit (vs. pre-unit) T-100A Trophy was introduced in 1960, a mild 500cc bike that made the step up from a scooter, or 125 easy, since the expense, heft and power of a full sized 650 might be too much for a new rider to handle. Tipping the scales at just over 340 lbs, the T100’s were much lighter and nimbler than the big 650’s, and in certain situations, like tight woods, or a short scrambles track, the 500 proved to be just as fast.
1967 T100-C, notice miserable monobloc Amal.
The pre-unit T-100C made its name in flat track competition, racing against 750cc flat head Harleys, since the formula back then was 500cc overhead valve vs. the 750cc flat head. And the 500cc Trophy seemed, err..a little more reliable than its bigger brothers, affording Triumph to sell every 500 it produced. Many were modified to the ragged edge, race only, but paid the price in reliability on the track, leaving the 500cc duties to the big singles like the Matchless and BSA, that seemed to accept horsepower extraction better than the 500 twin did, without blowing up, and scattering engine parts across the infield.
1969 T100-C. Note Amal Concentric carb. & stronger frame
The T100 also made a great machine for enduro competition, with a flat torque curve, and relative light weight, it won many medals in Six Day Trails competition. It also was used to some success in Eastern woods riding in the United States, many being modified with Hindal frames and Westlake hop-up parts to keep up with the two stroke Huskys.
But when left stock, a sweeter 500cc motorcycle couldn’t be found. The bikes started easy, even the electrics seemed to last longer than the 650’s (less vibration maybe). The 500 employed the classic Triumph firing order, where the pistons rose and fell at the same time, and fired on opposite strokes, one right after the other.
Motor internals, while smaller, copied the modified Edward Turner design faithfully. The unit design was compact, and some say better manufactured than the 650 was. The 500 twin is a very sought after Triumph in today’s vintage bike scene.
The street version used twin monobloc amals, with the street scrambler and dual sport c model using one 34mm Amal Monobloc. The 500 didn’t get modern carburetion until 1969, when the designation changed to the Trophy TR5T, and it got one leaky slide breaking Amal concentric (with the competition light-weight plastic float bowl).
A few were produced in 1974, but after the implosion of the British motorcycle industry in 1975, the sweet little T-100C 500 twin was left to the history books. Another end to a fine machine.
1973-1974 TR5T Trophy. The last one. I'll take mine on the rocks please.