1973 Triumph TR5T Trophy Trail 500
Triumph TR5T Trophy Trail 500
Claimed power: 30hp @ 7,500rpm
Top speed: 90mph (period test)
Engine: 490cc air-cooled, OHV vertical twin
Weight (wet): 350lb (159kg) (est.)
Fuel capacity/MPG: 2.4gal (9ltr) / 55mpg (est.)
Price then/now: $1,425 / $1,500 – $4,000
The 1973 Triumph TR5T Trophy Trail 500 isn’t a serious motorcycle, but that doesn’t mean it’s a bad motorcycle, either. The TR5T was built just to be a cheerful little number that could fill a niche in the market. Lightweight, with a good engine and an adequate chassis, it wasn’t a motorcycle intended for serious competition, but more a cycle built as an entertaining play-bike for those with hundreds of miles of forest roads or black-topped one-laners to ride.
In its day, the TR5T was quite the opposite of those great, honking 650cc desert sleds that were so popular in the scrub-lands of California and Arizona; this was an East Coast special, intended for more leisurely pursuits in the Berkshire Hills of Massachusetts or the Shenandoah Mountains of Virginia.
How we got here
In the early 1970s, the engineers at Triumph were trying to spiff up their line of models at the lowest cost possible, since Triumph was having severe financial problems. Triumph had been partnered with Birmingham Small Arms (BSA) for over 20 years, with the two brands kept very separate until the late 1960s, when the British motorcycle industry started collapsing with barely a whimper. At the Meriden factory, workers began cobbling together bikes by picking and choosing from the Triumph and BSA parts bins, and in 1971 some enterprising worker realized that with a few minor modifications, the Triumph 500cc engine could be fit into the new BSA scrambler-type frame.
The U.S. had always been Triumph’s best market, but sales of the high-piped street-scrambler T500C models had dropped off, thanks to cheaper Japanese machines. However, the marketing suits at the Meriden factory figured that a Triumph-powered woods bike might have good sales potential, so they built one.
Introduced for the 1973 model year, the Trophy Trail was known as the Triumph Adventurer in the U.K. Rumor had it that the Trophy Trail was, in truth, a tribute to the 1973 International Six Days Trial (ISDT) that was being held in the U.S. This was the first time since 1913 that the ISDT had a venue outside Europe. This new model was not intended to go up against ferociously focused machines put forth by outfits like Jawa, Husqvarna and John Penton, but would be the layman’s version, giving the image of derring-do while offering a modicum of comfort.
The ISDT was originally intended to be a reliability event, with the motorcycles running for six days, and repairs could only be done by the rider with tools he carried. This made a great deal of sense back before World War I, as roads were in pretty rough shape. After the end of World War II the event had been altered to fit a more modern format, with the course being run mostly on dirt roads and trails, with a bit of pavement in order to keep everybody honest as to lights and braking. Many manufacturers took winning deadly seriously, but not the boys designing the TR5T.
Tough, but not too tough
The Triumph TR5T Trophy Trail has a 490cc, over-square engine (larger bore than stroke, in this case 69mm bore by 65.5mm stroke), detuned a bit from the hot-rodded, twin-carbed T100R Daytona version in order to give the machine more tractability. Compression was a moderate 9:1 and carburetion was by a single 28mm Amal Concentric. This provides satisfying throttle for the lady or gent wishing to plonk along disused roads in the wilderness, with a claimed 30hp at 7,500rpm. A wise rider will keep the tach between 3,000 and 5,000rpm, which offers sufficient torque at one end and acceptable vibration at the other.
The key to its climbing and slogging abilities is the fact the bike came stock with an 18-tooth gearbox sprocket and 53-tooth rear sprocket, a combination that worked well with the bike’s 4-speed gear box. Claimed top speed when the bike debuted was a teeth-rattling 75mph, predictably slower than its sporting street-savvy Daytona sibling, which was good for over 100mph.
Ignition is by coils and points, with a 12-volt battery and an alternator. Of note is the exhaust system, with header pipes coming out of the cylinders to be siamesed as they disappear behind a small skid plate and run below the engine into an unobtrusive, fabricated muffler that mounts under the right-side swing arm. There is nothing round, smooth and chromed about this muffler. Instead it is an efficient, flat-black, elongated box that was quite acceptable to the U.S. Forestry Service. Some people didn’t like the aesthetics when the bike came out — aren’t dirt bikes supposed to have pipes lifted high in the air? — while others thought the muffler was clever, as its location kept the rider safe from burning a leg in the event of a fall-over.
A new frame of mind
The chassis is more interesting. It was the bright lights at Umberslade Hall, the R&D division of Triumph/BSA, who had come up with the oil-in-frame design in 1970. In principle the idea was sound, avoiding the need of a separate oil tank for the dry sump engine, but the downside reality check was that British engines occasionally had a tendency to implode when hard pressed, causing little particles of metal to float through the lubrication system. Blow your engine, and even if you flushed the frame thoroughly all it took was one little scrap to dislodge from its hiding place after the rebuild and SCRUNCH! … there goes another engine. The system holds just four pints, which is fine for modest efforts, but a trifle short when keeping the engine on the boil for a long period.
Other than that, it’s a pretty good frame, and one variation was used on the BSA B50 singles that appeared in 1971. At the Triumph plant in Meriden a B50 frame was brought in, a few alterations made to the mounting points, and the Triumph twin bolted in.
The swing arm uses the BSA motocross method of chain adjustment, with the entire swing arm moving fore and aft via snail cams at the pivot point, rather than merely pulling the wheel back. Though fine for a race, it certainly wasn’t built for six days of hard duty and an inevitable tire change or tire repair, as this means that the wheel isn’t quickly detachable. Rather soft Girling shocks keep the rider happy, but it is wise to be cautious when in rough terrain, as they could — and do — easily bottom out.
The front forks are the bare-naked Slimline version; they look good but lack in practicality, as they have no rubber gaiters to protect the seals and fork legs, only small rubber dust caps over the forks. Again, the front wheel isn’t quickly detachable, as each of the two axle clamps are held on by four bolts. The rake is 27 degrees, making it more of a street machine than trials, but that’s quite useful when going through soft sand, as it holds a straight line better. The claimed travel of 6.75 inches is acceptable for modest performance, but better suited for dirt roads than jumping ditches. The seat height is 32 inches, so the rider doesn’t have to have exceptionally long legs. The ground clearance, unladen, is rated at 7 inches, but a 200-pound rider will put a big dent in that. Distance between the axle centers is 54.5 inches.
The front tire is a 3 by 21-incher, and the rear a 4 by 18-inch. Brakes are a limiting factor, with a skinny single-leading-shoe 6-inch drum on the front and an 8-inch drum on the back. These are OK in the woods, but not quite what one needs on the highway when the car in front does a panic stop from 50mph.
The three-quarter-length saddle is nice and flat, good for moving about on, and if the rider scrunches up forward he or she can get a passenger on board (except the passenger pegs are on the swingarm, which goes up and down). This is best considered a solo machine.
The gas tank holds just 2.4 gallons, but thanks to good fuel mileage, that’s enough for more than 100 miles. A smallish headlight keeps the demons of night at bay, and a speedo and tach are sensible instruments, though the tach is barely necessary, as the solid-mounted engine tells the rider when it’s time to shift. Wet weight is in the vicinity of 350 pounds, heavy for a real dirt bike but light enough for a road machine.
There isn’t much to starting the bike as long as the battery has juice: turn the fuel on, tickle the carb, choke if necessary, pull in the clutch and kick through to clear the plates. Then let out the clutch and reach down to the right side panel to turn on the ignition, kick, and — bang, putter, putter, putter. At higher revs the notoriously noisy overhead valve gear echos off the metal gas tank.
The Triumph TR5T Trophy Trail was introduced in September of 1972 in Southern California, where most of the press wondered just what this thing was for. It did not have nearly enough power for the Barstow to Vegas offroad run, and was a misery on the 75mph Los Angeles freeways. But the East Coast understood the purpose, and the Triumph dealers there sold a good many of them. Also, Triumph had its eye on the ISDT and had a dozen bikes prepared for the Berkshire event a year later, half for the Yanks, half for the Brits. The Brit team came in second overall, and riders won a number of gold medals. However, it should be added that these models were extensively modified, with new forks, quick-detach rear wheels, altered exhausts, etc.
The Trophy Trail had a less than two-year run; by the end of 1973 the outlook at the Meriden works was so dire the factory went on strike, having built only a few 1974 versions of the TR5T. And when the factory did reopen in 1975, the decision had been made to stop production of all the 500 twins. It was the end of the line. Pity, because in its own little way, it was a fine little machine, even if it’s time had passed long before it was built. MC
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