Triumph Thruxton R 'deBolex Special'
By Ross Sharp - 03 May 18
As manufacturers produce better and better machinery upon which custom workshops apply their skills the bar continues to be raised, but there comes a point where visual modifications alone are unlikely to attract the most discerning customers. In a world where driving a Koenigsegg or Lamborghini in stock trim is considered slightly passé there's a certain expectation that a vehicle performs as well as it looks. This latest build from deBolex Engineering has been a test of determination and resourcefulness for Calum and Des in their quest to build a performance enhanced Triumph Thruxton R for a man with rather high standards, Prince Mateen of Brunei. Despite the Thruxton's traditional twin-shocked looks it's actually a fairly complicated bike to work on, packed with clever tech that allows it to excel in modern, regulation led times while delivering the character punters expect from a bike wearing the Thruxton moniker. deBolex wanted to embrace this technical side but enhance the riding experience by utilising their skills as master craftsmen and metalworkers to blend the right here and now with the good old days. Having grown up around 1950s & 1960s sports cars, Calum sees deBolex builds as an evolution of a time-honoured method of building a race car, or bike for that matter. Strip away anything unnecessary, reduce weight and replace perfectly good components with the best available. And the shopping list for the thurxton was to be quite something. It's a struggle to know where to start with this build as there's so much under it's elegant skin. The standard Triumph tank is a beautiful shape but it's steel, and everyone knows ferrous materials should be used for spokes, spindles, cranks, cams and bearings - and that's about it. The new fuel tank's shape was inspired by classic TT race bikes from a golden era, beaten by hand and pulled back and forth through the English Wheel until smooth, and a perfect fit to the pre-made wooden buck. The standard fuel pump was retained and mounted with a bespoke stainless steel flange and a Rizoma race filler cap offers a glimpse inside to check the fuel level, in case the Prince isn't familiar with the hip wiggle and listen for the sploshing method During a mid-build visit to the workshop I suggested to Calum that he make a custom radiator but thankfully, as is often the case, he ignored me and fabricated a beautifully curved aluminium shroud to cloak the stock rad, which is now protected and hidden slightly by stainless steel mesh. The aluminium belly pan serves to direct airflow to help cool the engine's sump but mainly it looks fast while providing a well needed home for some clever engineering. More on that in a minute. The tail, seat base, underseat pan, mudguards and nose/light unit were also painstakingly fabricated from annealed aluminium sheet. The headlight surround is a wonderful piece of fabrication in its own right. With a quarter turn of the fastener a circular cover piece can be removed, and stored in a soft bag under the saddle, to reveal a beam of light from the fully functioning and road legal lamp.
The Thruxton's stock brakes are also perfectly good, which is not quite good enough for deBolex. Blasted and reanodised Brembo .484 moonobloc calipers, complete with a gold B, and ISR floating discs are actuated by a Magura HC2 master cylinder. A matching pump, perch and lever on the other side mates to a Magura hydraulic clutch conversion for a particularly slick feel. Renthal clip-ons and grips were fitted along with Rizoma barend plugs. But that's not the trick part.
The eagle eyed will have spotted the reversion to a cable throttle. The notoriously tricky to modify ride-by-wire Triumph throttle was overcome by fabricating a two bearing conversion unit which sits down below in the bellypan. Venhill cabling links a traditional throttle assembly to the electronics below which has a lovely action and tidies-up the bars. But that wasn't the main reason for tinkering with the electronics.
The guys decided that it wouldn't be racy enough to simply lighten the bodywork and upgrade a bunch of parts, the R in this Thruxton actually needed to stand for something. So, the whole wiring harness and ECU was removed. Yup, this isn't just a Motogadget rewire (although it is running the M-unit system) to enable the fitting of tiny lights. No, this is a full-on motorsport spec loom from X-Bikes Racing allowing not only the extraction of more power from the under-tuned 1200cc Hinckley twin but range of adjustability too. If you've ever seen an F1 car or Moto GP bike with is clothes off you'll recognise the Deutsch Autosport Connectors used here. About as far from a squeeze-and-hope bullet connectors as you can find. If you've a perfectionist, engineering mind then loom alone on this thing should give you a semi.
Tackling this with zero input from the manufacturer is no mean feat. Triumph are rightfully guarded about what makes their stuff work and don't take too kindly to young upstarts in sheds fiddling with their hardwork. X-Bikes grafted a Microtec ECU into the minimal loom, married this to the converted ride-by-wire part of the throttle assembly and then spent a good few weeks refining the fuelling and ignition maps. There's a full-on race map and a tamer road mode, with potential for loads more tuning should the Prince feel the need for more speed. The throttle bodies have been machined-down to remove the faux Amal carb castings and a whopping K&N filter was plugged on the back. A handmade stainless exhaust and Keihan silencer with satin matt black ceramic coating is relatively straight-through and sounds awesome (video below) crackling through the gears wide open thanks to a Cordona quick shifter.
The full race-spec dyno run output figures aren't available just now but Calum's report from the track is that the throttle response is hugely improved and the engine spins-up much quicker than before. Sadly, given the hundreds and hundreds of hours that'd gone into the build I wasn't going to be finding out for myself anytime soon.
The rest of the wiring seems modest by comparison but is immaculately finished. Motone push button switches with internally fed wires activate Motogadget pin indicators and the starter, all powered by a lightweight Shorai lithium battery hidden under the swingarm. The slimline ECU and myriad of relays live under the water resistant Alcantara seat pad, upholstered in house, accessed using the original Triumph seat mechanism and key. A clean and simple yet functional Motogadget Chronoclassic instrument shows speed in a small digital display while the analog needle is more of a volume gauge, also logging engine revs.
Finally, the painstaking task of flatting the aluminium and prepping for paint. As mentioned in previous features, deBolex are still using the same pot of filler from about five years ago. The guys prefer to spend time ensuring the metalwork is immaculate prior to priming rather than masking whoopsies. Sticking with the Triumph theme Jet Black was chosen from the factory's palette for the bodywork with a flash of Racing Yellow on the headlight roundel.
Before delivering the Triumph Thruxton R deBolex Special to Prince Mateen the bike needed a proper shakedown. And what better place than Goodwood Motor Circuit, the source of so much inspiration for Calum and Des and the perfect arena for a high speed run. Sadly for Calum, luckily for Marteen, the heavens opened on the morning of the first test so speeds were limited by a damp track. Although that did make life a bit easier for Autohouse London and Wolli Films to capture the action.
I reckon that, given a time machine, Calum and Des would have been rivals to Colin Chapman & John Cooper, but perhaps with a slightly more couth logo on the side of their cars for the Goodwood crowds to cheer on. I'm glad that such things don't exist as deBolex builds go form strength to strength and we can't wait to see what they get up to next.....
Images by Autohouse London
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Special thanks to
Flying Tiger Coatings
Goodwood Motor Circuit
Enjoy this by Wolli Films, speakers up!!
TRIUMPH THRUXTON R 'deBolex Special' from Wolli Films Limited on Vimeo.
Calum talks Ross through the build and all the little details