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Retro Rescue: PBM’s custom Triumph Bonneville T140

Custom Triumph Bonneville T140 by Purpose Built Moto
I spend time around people who love old English bikes, and I feel like the Triumph Bonneville T140 cops a bit of flak from the Triumph crowd. Granted, its legendary predecessor, the T120, was a tough act to follow. But while the T140 doesn’t quite have the same allure, it does make for a brilliant custom in the right hands.

Built by the team at Purpose Built Moto from their Gold Coast workshop in Australia, this 1973 Bonneville T140V has been transformed into a very sleek desert sled. Vintage Triumphs aren’t usually their cup of tea, but the PBM gang were more than keen to handle something a little left field. And to make things even more interesting, the bike came to them in a sorry state.

Custom Triumph Bonneville T140 by Purpose Built Moto
“If you have a nice old bike and you want to keep it that way, make sure you use it,” says Tom Gilroy, ‘Chief of Escapades’ at Purpose Built Moto.

“This project came to us because it had been neglected for so long it was no longer running. Everything had seized up, and without some serious attention it was going to slowly fade away and crumble.”

Custom Triumph Bonneville T140 by Purpose Built Moto
To kick things off, the entire front end got one hell of a birthday. The forks and brakes were stripped down and rebuilt, with all new finishes applied. PBM fabricated a new front fender and brackets in-house, featuring a looped-over design not too dissimilar from a vintage motorcycle, albeit quite a bit shorter.

The wheel set is one of my favorite parts of this build. It consists of a new set of valanced rims for a bit more vintage flair, laced to the stock hubs. The trials-style rubber comes from Pirelli and certainly looks the part.

Custom Triumph Bonneville T140 by Purpose Built Moto
The original low profile Bonneville handlebars were retained, but retrofitted with vintage switches and new grips. PBM deleted the tachometer, then cleverly Frenched the factory speedometer into the Lucas-style headlight bucket, along with a set of warning lights. The factory headlight brackets were carried over too, with PBM’s own chrome LED indicators also acting as the headlight bolts.

Moving back to the fuel tank, it was decided that a riff on a factory design would suit the build well. Laid down by Justin at Popbang Classics, a fellow Gold Coast lad, the silver and off-white scheme oozes classic Triumph, but with a modern twist.

Custom Triumph Bonneville T140 by Purpose Built Moto
With the build progressing, attention was turned to the engine. The carburetors were rebuilt, the top end was adjusted and a new Boyer ignition was fitted.

“According to the owner, it used to run strong—and he was actually on the money,” explains Tom. “The motor was in great condition inside, so we polished up the outside to match, replaced the leaky gaskets and got it started on the second kick.”

Custom Triumph Bonneville T140 by Purpose Built Moto
All scramblers worth their salt feature a nice exhaust, and this one is no exception. Running high down the left side of the engine is a custom-built stainless steel system. A bit of back pressure never hurt anyone, so PBM used oversized piping so that they could hide some baffles in the end.

As someone who regularly experiences the sound of 744 cc Bonnevilles with lightly-baffled pipes screaming through tunnels, I bet this thing sounds spectacular at wide-open throttle.

Custom Triumph Bonneville T140 by Purpose Built Moto
Moving upwards, a new seat pan was cut to mirror the frame rails perfectly, and then topped with a nicely shaped piece of foam. The new seat was then sent down the road to Jamason at Timeless Auto Trimming, who stitched together a classic leather cover.

Out back are some more PBM parts. Their new rear fender kit cleans up the back end very nicely; it’s adorned with their own ‘Orbit’ taillight, and flanked by a pair of their LED turn signals. The old shock absorbers had seen better days, so they were promptly replaced with a brand new set that are 20 mm longer.

Custom Triumph Bonneville T140 by Purpose Built Moto
What do Tom and the PBM team think of the end result? It’s not exactly a surprising end note.

“Being our first vintage Triumph, I’d never actually ridden any of the old twins,” describes Tom. “About 3.5 seconds into the test ride I fully understood why these bikes were just so damn popular. The sound from the exhaust and rattle of the engine is what draws you in—then you rip back the throttle and realize that this dinosaur can move!”

Custom Triumph Bonneville T140 by Purpose Built Moto
“It is surprisingly fast and with the suspension upgrades, it’s a killer bike to get around on. Seeing as I had to hand it back to our client to enjoy for many years to come, I might have to add an old Triumph to my ever-growing list.”

Purpose Built Moto | Facebook | Instagram | Images by Brandan Trudinger

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