1956-57 Triumph 200cc Twin-Cylinder Two-Stroke Prototype Road Test

First-ever road test of one of Triumph’s secret prototype projects

One of the great overlooked opportunities of British motorcycle development in the days when the British industry led the world – only to lose this supremacy a decade later to the Japanese, who produced many millions of motorcycles just like this one

As motorcycle marketplace misjudgments go, it’s close – but not quite up there with Ron Wayne, who in 1976 founded Apple Inc. with Steve Jobs and Steve Wozniak, but 12 days later sold them back his 10% stake in the company for $800, after coming up with the first Apple logo via an ink drawing. Mmm – those shares would be worth around $67billion today! Likewise back in 1962 Decca record label exec Dick Rowe turned down the chance of signing the Beatles, telling their manager that "Guitar groups are on their way out, Mr. Epstein." He thus joined an elite mismanagement club of those whose names are synonymous with catastrophic commercial misjudgments, which includes all the many publishers who turned down a book about a magical boy wizard named Harry Potter by an unknown young writer named Joanne Rowling, and of course William Orton, then president of Western Union, who in 1876 decided not to pay $100,000 to Alexander Graham Bell for his patent for the telephone, declaring the apparatus to be “little more than a toy”. Still, while there are many other members of the misjudgment mafia, quite a few of them put their mistakes behind them – like Rowe, who went on to sign the Rolling Stones, although only after the Beatles, having teamed up with rival label Parlophone, had demonstrated that guitar groups were still very much in!


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Triumph’s chief engineer and later CEO Edward Turner fits into the Rowe mould, because he did repair his reputation with the serial success his Triumph 500-650cc ohv twins enjoyed in the USA in the Swingin’ ‘60s. But before that in 1957 Turner had his Beatles moment, when he ordered his R&D team at Triumph’s Meriden factory to chuck a prototype engine they’d been working on under his direction into the bin. Fortunately, even though Turner had a track record of sending anyone who disobeyed him to repair police bikes in Saudi Arabia or set up a service network in Nigeria, the development guys didn’t scrap it, and the result is that the bike that might have made Triumph’s global fortune several times over before any of its products ever set a wheel on the Bonneville Salt Flats, is today on display at the Sammy Miller Museum www.sammymiller.co.uk for all to see and hear in action, having been restored to running order 20 years ago after the typically astute Mr. Miller acquired it back in 1995, as just a prototype engine and frame. 

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OK – but what is it? Well, in 1956, the year after Yamaha’s motorcycle division was founded, and Suzuki had been making small single-cylinder bikes only for three short years, Turner decided to have his Triumph design team build an experimental 200cc twin-cylinder two-stroke engine of the exact same type which duly propelled the products of Japan Inc. to worldwide supremacy in coming years. Well, except for Honda, whose boss Soichiro Honda always disdained the so-called ‘stink wheels’ as crude and dirty inventions which had no place in his company’s lineup – except, that is, for powering the first-ever Honda Dream motorcycle he built in 1949! Edward Turner essentially shared Pops Honda’s opinion – except that he was interested in possibly using such an engine in the Triumph Tigress scooter due to be launched in 1958 as the BSA Group’s entry into the then-booming scooter market dominated by the Italian Vespa and Lambretta two-stroke singles. In the event, the Tigress and its badge engineered BSA Sunbeam sister were powered after their October 1958 launch by either a 10bhp 249cc four-stroke twin-cylinder motor, or a 7.5bhp 173cc two-stroke single, both of them air-cooled. The two-stroke was a development of the BSA Bantam engine, but the four-stroke was a completely new parallel-twin with gear rather than chain drive to the gearbox. 

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Moreover, Turner had another reason for developing this 200cc stroker, which had more to do with internal BSA Group politics than anything else. In 1936 the then-struggling Triumph concern became a subsidiary of Ariel Motors, owned and run by the most astute and undoubtedly most far-sighted man in the British motorcycle industry both before and after WW2, Jack Sangster. He switched Edward Turner, who already worked for him at Ariel, over to Triumph to improve its product range, and this resulted in the Triumph Speed Twin introduced in 1938 with a parallel-twin 500cc engine designed by Turner, which would form the genesis of a range of successful Triumph parallel-twin motorcycles right up to the present day. In 1944 Sangster sold Ariel to the BSA Group for a considerable sum, followed in 1951 by the sale of Triumph to BSA for £2.5 million, which was a good return on the £50,000 he’d invested in buying the firm in 1936! Sangster joined the board of BSA after it acquired Triumph, becoming chairman of the BSA Group in 1956, following a series of boardroom battles with his predecessor, Sir Bernard Docker – owner of the notorious gold-plated Daimler limousine. Sangster then appointed Turner as CEO of BSA’s Automotive Division, comprising BSA, Ariel, Triumph, Daimler cars and Carbodies – the makers of London taxicabs. 

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This meant that when in 1958 Ariel introduced the fully enclosed Leader powered by a 250cc two-stroke engine aimed at combining the benefits of a motorcycle with the advantages of a scooter, Turner had ultimately overseen the development of this package. Together with the Arrow, a stripped-down more conventionally styled version of the Leader, which however retained its enclosed chaincase and valanced mudguards, this was what proved to be an unsuccessful attempt to bring BSA Group’s traditional British brands into the modern era mechanically, as well as stylistically. But presumably just in case the new Ariels strokers proved to be a hit – they weren’t, really, with Ariel producing a combined total of 35,500 Leaders and Arrows between 1958 and the end of Ariel motorcycle production in 1967 – Turner obviously decided to have a comparable Triumph equivalent developed at its Meriden base outside Coventry, well away from the Ariel factory at Selly Oak, a suburb of Birmingham 20 miles to the northwest,

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The new Triumph two-stroke engine was an air-cooled parallel-twin with reed-valve induction directly into the crankcase via a single Amal Monobloc carburettor, and a one-up/one-down 180º crankshaft. It had both cylinders cast together in one piece, as was the cylinder head, and there was a belt primary drive with the pulleys running on needle rollers, which replaced the chain primary used on all Triumphs to date, apparently in the interests of noise reduction – necessary for scooter use. Supposedly, much of the design was copied from the Evinrude Chore Horse, a rugged and very popular American motor that originated in 1935 to power washing machines, generators, pumps and lawnmowers. This was manufactured in the USA and Canada by a division of OMC/Outboard Marine Corporation, manufacturers of Johnson and Evinrude outboard marine engines until production ceased there in 1952. The Chore Horse was built under licence in many places during and after WW2, including by BSA in Britain, and production of the 24-volt BSA version continued well into the 1960s until the Army was equipped with transistorised radio sets that needed less power. 

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Supposedly, another reason for the engine’s creation was that Turner was considering teaming up with Bill Johnson (no relation), CEO of Johnson Motors in Los Angeles, Triumph’s West Coast American importers since 1944, to enter the fast-growing American personal watersports market. The thought that it might form the basis of a new range of lightweight motorcycles, perhaps replacing the Tiger Cub that had been introduced in 150cc guise in 1954, and would shortly increase in capacity to the same 200cc capacity as the two-stroke prototype motor for 1957, strangely doesn’t seem to have been a key priority.

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The Sammy Miller Museum in New Milton, Hampshire, UK, is crammed full of interesting machines – including factory prototypes and numerous ingenious designs from all over the world. There’s one of the world’s largest collections of exotic racing bikes, all of them in running order and including the legendary V8 Moto Guzzi 500, supercharged V4 AJS 500 and postwar Porcupine – the first ever 500cc World Champion, V-twin Husqvarna 500, V4 Suzuki 125, 250 Mondial with dustbin fairing, and innumerable famous bikes from Triumph, Norton, AJS, Velocette & many more! And of course there are plenty of offroad enduro, motocross and trials icons. The Museum is open to visitors daily from 10am year round.
The museum address is Sammy Miller Motorcycle Museum Trust, Bashley, New Milton, Hampshire B25 5SZ. Tel 01425 620777/616644 or visit www.sammymiller.co.uk for further details.

However, in building the prototype engine, Triumph engineers needed a cover for the Lucas alternator which provided current for lighting, as well as powering the 6v battery/coil ignition. So development fitter Dennis ‘The Menace’ Austin was sent off to the kitchen section of Leeke’s department store in Coventry clutching a Lucas RM13 stator, with orders not to return until he had found something suitable to cover it with. He returned to Meriden some time later with a saucepan which was apparently an exact fit for the stator, and after the top and handle were removed, and two Tiger Cub engine mounting lugs welded on, the bottom was cut out and the cover thus fabricated. Job done!

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The prototype 200cc two-stroke engine was then apparently run for some time in a water tank, where it was tested for power output. Initially it ran well, but as the test hours built up, performance fell away. Different reed valves, exhausts and inlet tract lengths were all tried, but to no avail – until it was eventually discovered that the cylinder liners had been slowly rotating until the inlet and exhaust ports were almost completely shrouded! The liners were pegged in place to resolve this, and testing resumed. But power output was disappointing, although designer Turner apparently disputed the test findings. John Nelson, who was in charge of Triumph’s development shop from 1947 to 1956, therefore bolted the engine into a modified Tiger Cub frame loop with a four-speed Cub gearbox and dry six-plate clutch attached to it, initially via a conventional chain primary drive, with the belt primary drive held in readiness for comparison testing. The result was mounted in a mobile test rig for demonstration to Edward Turner outside the Meriden factory gates, with outriggers either side to give the slave machine a rolling start. In this guise, with a chain primary, power improved quite dramatically, but with the primary transmission converted to belt drive, it was then found that this was using up as much as one-third of the engine’s entire output! So the chain primary was then reinstalled, but by then Turner had apparently lost interest in the project, and a short while later he decreed that it be scrapped, with the engine and its vestigial frame being laid to rest out of his sight in the factory cellar. So Yamaha had another couple of year’s grace to develop the YDS-1, its first two-stroke twin-cylinder streetbike of which it would make several million such units in the coming decades…

With the closure of the Meriden factory after the bankruptcy of the Triumph Workers Cooperative in August 1983, in preparation for its ensuing demolition by John Bloor to build a housing estate the sale of all the assets, machinery, fixtures etc. saw a selection of Triumph prototype engines exhumed from the famous cellar, and acquired by Derek Chapman and his son Michael, proprietors of Evesham Motorcycles not far away in Worcestershire. This included the 200cc two-stroke twin motor and its Tiger Cub-derived chassis, which when the Chapmans put their collection of factory memorabilia up for sale at nearby Stratford-upon-Avon on October 13, 1984, was acquired by a Mr. F.M.Chivers for £85 cash! He did nothing with it for the next decade, but in September 1994 Chivers offered it to Sammy Miller, who bought it from him for £350 – nice work if you can get it! “When I was working at Ariel in 1956, we were about to launch the Leader and Arrow as part of a complete switch to two-strokes, in designing which we’d had Val Page do a really brilliant job on both bikes,” recalls Sammy. “We heard that Triumph was working on something similar themselves, but then the word came back in 1957 just as our two-strokes came out that they’d chucked it in the bin because the great Edward Turner didn’t like two-strokes, and apparently didn’t think they suited Triumph’s masculine image! Of course, the Japanese then took the same identical format, and went on to make millions of them, starting the following year. What a terrible missed opportunity that was for Triumph!”

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Having obtained the prototype what-might-have-been Triumph stroker, Sammy then used period Tiger Cub running gear to rebuild it as a complete bike together with Bob Stanley, the Miller Museum’s mechanical magician, whose accumulated expertise acquired down the years in working with Sammy in restoring the most exotic and/or unlikely two-wheeled designs to running condition, must be unequalled by anyone – just take a walk through the host of rare exhibits on display which Sammy has tracked down and the two of them have made runners out of, as confirmation of that. The 200cc Triumph twin was one more of those, though it apparently needed very little work to make it a runner, apart from sourcing Tiger Cub wheels, suspension and brakes to hang on the chassis to make it rideable. “The engine was like new inside,” says Bob Stanley, “so it had obviously spent very little time running on the dyno. The only thing we changed was to fit a Mikuni carb instead of the Amal it came with – Mikuni make such nice carbs for use on two-strokes that it made everything much easier, and you can’t see it, anyway.” Presumably the reason for such a long inlet tract is simply cosmetic, to be able to tuck the carb away behind the side panels introduced on the T20 Tiger Cub for 1958, but modified to suit the absence of any oil tank – the engine runs on a 4% petroil mix.

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Being unregistered – although, like 90% of the contents of the Miller Museum, fully functional and rideable – the chance to ride the Triumph two-stroke (saying that seems such a contradiction in terms!) for myself came on the long private driveway leading to a magnificent country home near the Miller Museum, as well as along Sammy’s tighter test track weaving its way around the Museum grounds. This allowed me to simulate everyday use on the little bike, once I’d easily kickstarted into life via my right foot, leaving it to purr away at a fairly fast idle through the twin exhausts. These are conventional in design – Walter Kaaden’s MZ secrets had not yet escaped to the West via the refugee Ernst Degner – but even so Bob Stanley reckons that the little engine produces around 20 bhp at between 8,000 and 9,000 rpm, and that sounds right, judging by the distinctly spritely acceleration the little bike delivers once you notch bottom gear on the one-down, three-up right-foot four-speed gearchange, with its very light-action clutch. The small 80mph speedo nestling in the top of the headlamp nacelle indicated 70 mph in top gear with more to come, before I thought it best to throw out the anchors, in best Fifties slang! That was a wise move, because the small six-inch single-leading shoe/SLS drum front brake is distinctly on the feeble side with zero engine braking to help out, so you must stamp quite hard on its slightly larger seven-inch rear sister to obtain decent deceleration.

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The 51inch/1295mm wheelbase of the prototype stroker’s Tiger Cub frame does make the little Triumph seem pretty diminutive, but it’d be quite comfortable for someone of my 1.80m/5’10” height to use for commuting or running errands. You do have to coax it into the powerband via the clutch lever when exiting slow corners, however – though the reed-valve engine is quite torquey, it’s also just 200cc in capacity, so you need to make allowances. But there’s absolutely no vibration from the parallel-twin engine, even when you rev it harder to keep it on the pipe when you hit a higher gear. What a shame Edward Turner wasn’t more patient, and didn’t give his R&D team more time to develop this sweet little engine. And full marks to Sammy and Bob Stanley for their work in building the bike totally ‘blind’, devoid of any reference material to achieve this. In doing so, they’ve demonstrated that Edward Turner really overlooked a golden opportunity to beat the Japanese to the punch.  History records that instead, they duly delivered Triumph the knockout blow exactly a decade later with the debut of the four-cylinder Honda CB750….

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But now under John Bloor’s ownership Triumph is once again looking at making the small-capacity motorcycle in India that they nearly launched five years ago at their putative Indian factory that ended up never getting built (bike and factory, both), but this time in conjunction with local giant Bajaj Auto. I wonder if it’ll be a two-stroke twin, like this one from exactly 60 years ago?!

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One thought on “1956-57 Triumph 200cc Twin-Cylinder Two-Stroke Prototype Road Test

  1. Very interesting article. Had a 4stroke Cub in 1959, and now have a 61 model. This 2 stroke was unknown to me even though I have visited Sammy MillersMuseum many times as I live in the same County. Thanks for increasing my motorcycle knowledge. As they say you are never too old to learn, and I am 82.

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