The early 1970’s saw an innovative period of motorcycle development. It was an era of evolution, with engineers building on previously proven models and increasingly refining each manufacturer’s respective two-wheeled offerings. Triumph’s TR6 shares its lineage with the majority of its vertical-twin powered machines, tracing back to the ’38 500cc cast iron Speed Twin. After things calmed down a bit following WW2, Triumph resumed production of the Speed Twin, with manufacturers like BSA, Norton, Royal Enfield, and Matchless all “borrowing” the mill’s design. Not to be outdone, in 1950 Triumph bumped the displacement up to 650 via the 6T Thunderbird.
Other manufacturers struck back and something of an moto arms race began. Triumph’s rebuttal was the ’53 Tiger T110, the name supposedly comes from the bike’s 110 mph top-speed. Other mocos returned fire and in ’56 Triumph once again upped the ante with the TR6, which was a noticeable improvement thanks in part to what was called the “Delta Head”. The updated scoot featured a new aluminum alloy cylinder head, it boasted larger valves that enabled superior flow while being lighter than its predecessor. It also sported better cooling thanks to more fins. Triumph took advantage of this and opted to use higher compression ratios.
The TR6 still breathed through a single Amal Monobloc carb, but was considerably more stripped down compared to the 6T and T110 models. While Triumph was a popular brand in its native UK, the American market was clamoring for desert racers and scrambler machines. The British manufacturer aimed to nab a piece of this market, so it came as little surprise when the TR6 came with narrow alloy fenders and a headlight that was easily removable thanks to quick-detach wire connectors. It was around this same time – towards the end of the 1950’s – when Triumph shook things up in a pretty major way by opting to produce unit construction powerplants, housing all three main component sets (the engine, primary, and gearbox) in one common set of cases rather. This enabled cheaper production costs and better reliability, especially as engines were becoming increasingly powerful.
Triumph started making unit production setups on its 3T and 5T models (350cc and 500c) before the TR6 would get the treatment. By ’63, the new Triumph TR6 had been debuted, along with the 1963 Triumph T120 Bonneville line that included an all new unit construction engine and an entirely new chassis. These models were met with good sales numbers, and Triumph found themselves building a lot of bikes – many of which were bound for the States. Luckily for Triumph, the unit construction enabled faster production as well so this was an obvious win/win for the iconic British company. By the end of the ’60’s, Triumph was was doing incredibly well, going on to release the ’69 and ’70 models which were widely regarded as some of its best of all time.
But as Triumph enjoyed success, other companies stepped in and raised the bar until Triumph realized actions needed to be taken. The Bonneville and TR6 had grown a little long in the tooth and both necessitated updates, so BSA – who owned Triumph at the time – put its people on it at its then state-of-the-art technology center: Umberslade Hall. Unfortunately what the developers and engineers came up with wasn’t a five-speed transmission, an electric starter, less violent vibration, a front disk brake or more dependable electronics. Instead however, BSA’s finest somehow felt what the Triumphs needed was an oil-bearing frame that would eliminate the need for an external oil-tank. BSA invested an enormous amount of time and resources into the new frames, and to justify this it was decided that not only would Triumph 650 twins utilize the new oil-bearing frame, but BSA A50 and A65 models would too.
The development of the frame slowed production and cost valuable time, but another surprise was in store for the UK-based mocos. When the frames finally arrived at the factories, it turned out the engines couldn’t be dropped in without first having to remove their rocker boxes. This resulted in some very necessary problem solving, but fortunately some last minute engineering work not only resolved this problem via some new designs, but actually improved the original design in the process. In the end, the ’71 models would have the oil-in-frame chassis.
1972 was the second year for these frames, and Triumph released four model variants of the TR6: the TR6R, which was the standard Roadster with low pipes, the TR6C which had high pipes running alongside the bike’s left, the TR6P which was a police version, and finally the TR6RV, a Roadster with an optional five-speed gearbox. ’72 also saw a slightly more sensible seat-height of 32”, instead of the previous 34.5” height. In ’73 the TR6 would be replaced by the new 750cc TR7 Tiger. The TR7 would finally get a standard five-speed and the front disk brake it had needed for so long.
1971 also saw the introduction of conical brake hubs, front & rear, with all new brake hardware. ’72 saw a myriad of improvements including revisions to the oil-in-frame chassis and polished lower sliders that no longer had the styling rib found on previous models. Other engine and gearbox updates made to models at the start of the decade would also make their way onto the ’72 and ’73 models. Obviously I’m leaving out a fair amount of detail here because full-length books have been written about this and this is just a daily post, but we’re now up to the 1972 TR6R, which is the example that is currently for sale.
The ’72 TR6R – which again was the standard roadster version with low pipes – was powered by an air-cooled 649cc OHV vertical twin that reportedly made 47 hp at 6,700rpm. Married to the British twin was a wet multi-plate constant mesh four-speed that was controlled via the right-side foot-shifter. The ’72 TR6 models – including the TR6R – all wore the new conical hub units, paired with suspension comprised of a telescopic fork with two-way hydraulic damping, and a swingarm that was softened by two Girling dampers. The ’72 TR6R had a supposed weight of 383 pounds.
This particular example also boasts matching engine and frame numbers, and has 13,040 miles on its 45-year-old odometer. The right-side shift that’s found on this example is a pretty snazzy feature too. This example also recently underwent maintenance including having both the engine, primary, and gear oils changed, a brand new battery was installed along with new fuel-lines. This example also sports an upgraded megaphone pipe and aluminum indicators and it reportedly boasts an electrical system that is working flawlessly.
The same seller of this Triumph example is clearly a fan of early 70’s British 650’s, as they’re currently also selling a 1972 BSA Lightning A65 650cc in equally solid condition for pretty much the same price. ClassicBritishSpares’s (CBS) Mikyle Ede did a really cool story last year about how he ended up in possession of his ’68 Tiger TR6R, I really enjoyed it and recommend checking it out.
You can find this 1972 Triumph Tiger TR6R with matching frame and engine numbers for sale here on Craigslist in Miami, Florida with a price of $4,000.