When Tri­umph’s Tro­phy Trail first hit the dirt roads, ISDT rid­ers rapidly made mod­i­fi­ca­tions to im­prove its per­for­mance. Roy Mad­dox meets an owner who’s con­tin­u­ing that grand tra­di­tion with his own 500 twin…

Real Classic - - What Lies Within - Pho­tos by Roy Mad­dox / Kevin Brown / Mor­tons / RC Ar­chive

When Tri­umph's Tro­phy Trail first hit the dirt roads, ISDT rid­ers rapidly made mod­i­fi­ca­tions to im­prove its per­for­mance. Roy Mad­dox meets an owner who's con­tin­u­ing that grand tra­di­tion with his own 500 twin ...

Back in the 1960s, our Amer­i­can cousins were good cus­tomers for Tri­umph’s off-road ori­ented ma­chines, but sales of the high­piped street-scram­bler T100C mod­els had dropped off with the ad­vent of cheaper Ja­panese trail ma­chines. How­ever, the mar­ket­ing suits at the Meri­den fac­tory fig­ured that a Tri­umph-pow­ered trail bike might still 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 UK. Ru­mour had it that the Tro­phy Trail was ac­tu­ally a trib­ute to the 1973 In­ter­na­tional Six Days Trial (ISDT) that was be­ing held in the US; the first time since 1913 that the ISDT had been run out­side Europe.

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 car­ried on the ma­chine. This made a great deal of sense back be­fore World War 1, as roads were in pretty rough shape. Af­ter the end of WW2 the event had been al­tered to fit a more mod­ern for­mat, with the course be­ing run mostly on dirt roads and trails and a bit of tar­mac in or­der to keep ev­ery­body hon­est as to lights and brak­ing. Many man­u­fac­tur­ers took win­ning deadly se­ri­ously, but not the boys de­sign­ing the TR5T. This new model was not in­tended to go up against fe­ro­ciously fo­cused ma­chines put forth by out­fits like Jawa, Husq­varna and KTM, but would be the lay­man’s ver­sion, pro­vid­ing the im­age while of­fer­ing a mod­icum of com­fort.

The TR5T has a 490cc, over-square en­gine (larger bore than stroke, in this case 69mm bore by 65.5mm stroke), de­tuned a bit from the twin­car­bed 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 pro­vided sat­is­fy­ing throt­tle re­sponse for green­lan­ing or to plonk along dirt roads, with a claimed 30bhp at 7500rpm. A savvy rider would keep the tacho be­tween 3000 and 5000rpm, which of­fers suf­fi­cient torque at one end for rapid(ish) progress and ac­cept­able vi­bra­tion at the other.

The key to the Tro­phy Trail’s climb­ing and slog­ging abil­i­ties can be found in its gear­ing: it came stock with an 18-tooth gear­box sprocket and a 53-tooth rear sprocket, a com­bi­na­tion that worked well with the bike’s 4-speed gear­box. Claimed top speed when the bike de­buted was a teeth-rat­tling 75mph, pre­dictably slower than its sport­ing Day­tona sib­ling, which was good for over 100mph.

Ig­ni­tion is by coils and points, with a 12V 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 a fab­ri­cated si­lencer that mounts un­der the right-side swing­ing arm. There is noth­ing round, smooth and chromed about this si­lencer. In­stead it is an ef­fi­cient, flat-black, elon­gated box that had to be ac­cept­able to the US Forestry Ser­vice.

The chas­sis is a pretty good frame, a vari­a­tion of the one 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 swing­ing arm uses the BSA mo­tocross method of chain ad­just­ment, with the en­tire swing­ing 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 tyre change or tyre re­pair, which means that the wheel isn’t quickly de­tach­able.

The front tyre is a 3 by 21-incher, and the rear a 4 by 18-inch. Brakes are a lim­it­ing fac­tor, with a skinny sls 6-inch drum on the front and an 8-inch drum on the back. The three-quar­ter-length sad­dle is nice and flat, good for mov­ing about on. De­spite the pres­ence of pas­sen­ger footrests, the TR5T is best con­sid­ered a solo ma­chine.

The petrol 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 tacho are sen­si­ble in­stru­ments, though the tacho is barely nec­es­sary, as the solid-mounted en­gine tells the rider when it’s time to shift. Wet weight is in the vicin­ity of 350lb, heavy for a real dirt bike but light enough for a road ma­chine.

When the TR5T was in­tro­duced in Septem­ber of 1972, Tri­umph had its eye on the ISDT and had a dozen bikes pre­pared for the Berk­shire USA event, half for the Yanks, half for the Brits. The Bri­tish ISDT team came in sec­ond over­all and in­di­vid­ual rid­ers won a num­ber of gold medals. How­ever it should be noted that these mod­els were ex­ten­sively mod­i­fied, with new forks, quick-de­tach­able rear wheel, al­tered ex­hausts, etc.

Early on in their pro­duc­tion, 12 rather spe­cial Tro­phy Trails were con­structed, six for US rid­ers se­lected by Tri­umph and the re­main­ing six for Bri­tain’s Tro­phy and Vase team mem­bers. Prep work for all 12 took place in Bal­ti­more and it soon be­came ap­par­ent that it had it had been a very thor­ough job. They were still recog­nis­able TR5T mod­els but the front forks were now Ital­ian Be­tor units with quick-re­lease Rick­man con­i­cal hubs. Light­ness was achieved by em­ploy­ing the rolling chas­sis of the oilin-frame BSA B50 Vic­tor MX sin­gle mated to the sin­gle-car­bu­ret­tor 5TA Speed Twin en­gine unit. Electrics were sim­pli­fied with bat­tery-less coils and di­rect light­ing with all equip­ment held un­der a Vel­cro tar­pau­lin tri­an­gle within the frame and com­plete with three coils (a spare just in case).

In cus­tomer form 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 re-open 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 ma­chine. One man’s ma­chine

As the TR5T cel­e­brates its 45th birth­day it’s be­come a de­sir­able clas­sic – af­ter a few decades of lone­li­ness and ne­glect. I have al­ways been a fan, although never an owner, and remember be­ing im­pressed with the model’s ca­pa­bil­ity dur­ing my trail rid­ing days. The orig­i­nal ISDT rid­ers dis­cov­ered that the Tro­phy Trail ben­e­fited from sym­pa­thetic mod­i­fi­ca­tion, and the same is cer­tainly true now that the bike’s reached its po­ten­tial ‘midlife cri­sis’ point. Our fea­ture bike be­longs to Kevin Brown, who spends his work­ing day at Hitch­cocks Mo­tor­cy­cles (the su­perb pur­vey­ors of all things Royal En­field) and he’s the proud owner of a much mod­i­fied ex­am­ple of Tri­umph’s lit­tle gem.

He started with an orig­i­nal ex­am­ple with the in­ten­tion of bring­ing it back to its for­mer glory, and then Kev be­gan imag­in­ing ways in which the TR5T could be im­proved. Dur­ing his own­er­ship, he’s cre­ated the per­fect ma­chine for him. While there can be no doubt that the stan­dard of work­man­ship is first class and the over­all ef­fect is very pleas­ing to the

eye, this is no frag­ile show ma­chine. It is a prac­ti­cal bike that is rid­den to work, used for green-lan­ing and tour­ing.

It is ac­tu­ally quite dif­fi­cult to find an el­e­ment of Kev’s TR5 that has not ben­e­fited from his up­dat­ing and mod­i­fi­ca­tion. All of his changes qual­ify as im­prove­ments and to my mind he has pro­duced the ma­chine that Tri­umph could (…should…) have built. The over­all im­pres­sion is of a mod­ern mo­tor­cy­cle with a clas­sic heart. It’s a neat, func­tional, slim, shiny, ca­pa­ble off-road mo­tor­cy­cle that will cope with mod­ern road traf­fic. Kev has car­ried out his im­prove­ments while still rid­ing the bike, an on­go­ing work­ing project. His daily ex­pe­ri­ence with the Tri­umph led to the next im­prove­ment, and no area of the ma­chine is free from his at­ten­tion.

The front al­loy mud­guard has brack­ets un­der­neath bonded to carry studs to fit the loop to the forks, so there are no vis­i­ble fix­ings on the top of the mud­guard. While func­tion is very im­por­tant, Kev con­sid­ers the look of the thing all the time. A righ­tan­gle throt­tle was fit­ted to keep ca­bles tidy. It was orig­i­nally sup­plied in black and has been fetched back to the al­loy and pol­ished to house a one-off cable. Just get­ting the han­dle­bars right was a small chal­lenge, as Kev ex­plains. ‘ The USA-style cowhorn bars pulled back too far and were too high. I got some trial-style bars and cut about 30mm off each end, drilling them to pull the wiring through.’

The seat, sourced from Hitch­cocks’ stock, has been mod­i­fied with al­loy brack­ets to align tidily with the side pan­els. The rear rack is an­other one-off cre­ation held in place with an al­loy bracket fash­ioned from an al­loy block,

and it dou­bles as a bungee hook. Un­der­neath the rear mud­guard an al­loy tube car­ries and pro­tects the wiring. The rear in­di­ca­tors are at­tached to the frame by studs and the wiring goes through the frame – no un­sightly wires here. A wooden for­mer was used to cre­ate and shape the nar­row in­di­ca­tor de­sign.

The rear brake is con­verted to cable op­er­a­tion with knurled knob ad­juster. The front brake is the next on the ‘to do list’ with a beefier but ap­pro­pri­ate 2ls. Kev’s plan is that the twin lead­ing bar and ad­juster will be con­cealed in­side the brake plate: ge­nius.

The en­gine also re­ceived the at­ten­tion of Kev’s mag­i­cal hands and was to­tally re­built, with the crank dy­nam­i­cally bal­anced. He fit­ted elec­tronic ig­ni­tion but was un­happy with the en­gine’s low speed re­sponse so re­verted to points ig­ni­tion and PVC coils.

‘When first us­ing it,’ says Kev, ‘I no­ticed the oil at the rear of the frame never got hot. It’s lower than the point where the oil drains down the front tube to feed the oil to the pump.’ So the Tri­umph’s en­gine lu­bri­ca­tion was im­proved by the ad­di­tion of fil­ters and a two-into-one oil feed which over­comes the oil-bear­ing frame’s low spots. ‘I made a con­nec­tion via the rear drain plug through a fil­ter to a T-sec­tion of pipe un­der the en­gine to join front and rear feeds to the pump. It now uses all the oil in the frame.’

An Amal Pre­mier carb is fit­ted and breathes through a K&N fil­ter. Says Kev, ‘My Tri­umph only has a nine litre petrol tank so I’ve worked to keep it eco­nom­i­cal, which meant jet­ting down the Pre­mier carb. I man­aged (when I had no choice!) 165 miles with­out go­ing onto re­serve.’

The ex­haust header pipes have a rep­u­ta­tion for com­ing out of the head or rat­tling loose. So brack­ets were made with left and right threaded turn­buck­les to tighten against the head. The ex­haust and si­lencer is an­other one-off com­bi­na­tion with a twointo-one that runs un­der the en­gine and over the cross bar of the frame. A stain­less steel bracket sup­ports the bash plate, and the

si­lencer was mod­i­fied to clear the tyre.

The lat­est tweak to Kev’s Tro­phy Trail is an un­der­slung han­dle­bar mir­ror which was de­signed, cre­ated and fit­ted by the mas­ter fet­tler for safety on his next Euro­pean trip. As you can see, the bike is still a work in progress, with mi­nor mod­i­fi­ca­tions be­ing made when­ever the need be­comes ap­par­ent.

Kevin Brown has man­u­fac­tured what could be con­sid­ered the per­fect mo­tor­cy­cle. It com­bines the best of her­itage and in­no­va­tion with style and func­tion­al­ity. While the purists might baulk at the plethora of im­prove­ments over the orig­i­nal, Kevin will con­tinue to iden­tify the need for and de­vise more mod­i­fi­ca­tions for his TR5T – just like ISDT rid­ers did in 1973.

Left: Kev’s TR5T when first fin­ished. Its evo­lu­tion has con­tin­ued since this pic was taken, and these days it’s fit­ted with a dif­fer­ent sad­dle, nar­rower at the front to ac­com­mo­date owner Kev’s short legs

Above: The clean lines of the Tro­phy’s near­side; this ma­chine owned by Ger­ald in the USA and re­stored with spares from BritCy­cle

Arthur Brown­ing on his Tri­umph causes a splash dur­ing the 1973 ISDT. Arthur was an out­stand­ing rider be­ing suc­cess­ful in tri­als, en­duro and scram­bling as well as be­ing a pro­fes­sional speed­way rider

1973 ISDT ma­chine shows nu­mer­ous mod­i­fi­ca­tions, in­clud­ing plas­tic mud­guards and an­other so­lu­tion for the ex­haust

ISDT Motto: ‘Be pre­pared’ – fit­ted with three coils just in case. This way you al­ways have a spare

This truly is one well­sorted ma­chine

Above: Some thought the si­lencer on the Tri­umph TR5T Tro­phy Trail 500 was clever; its lo­ca­tion kept the rider safe from burn­ing a leg in the event of a fall-over. Oth­ers thought it was crapRight: The 500 twin en­gine’s pri­mary side re­ceives the clos­est scru­tinyBelow left: Neat touch: the bracket for Kev’s un­der-bar mir­ror (which dou­bles as a clutch lever clamp), prior to chroming

Below right: The fin­ished mir­ror fit­ted, ready for ad­ven­ture and mod­ern traf­fic

This bike doesn’t sit in the shed to be wheeled out when it’s time to show off. It’s a work­ing bike that meets the needs of the owner ex­actly…

The off-side shows the most work, in­no­va­tion and cre­ativ­ity

Bonded brack­ets pro­duce a mud­guard with no vis­i­ble fas­ten­ers

Ex­haust brack­ets were made with left and right thread turn­buck­les to tighten against the head

Com­pact rear end with pur­pose­ful de­signed and man­u­fac­tured rack and in­di­ca­tors

Above: Kevin’s so­lu­tion to the grotesque fac­tory fit­ted si­lencerRight: A pretty power plant with mod­i­fied oil lines

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