1963 Triumph Bonneville

1963 Triumph Bonneville Background & History

The 1963 Triumph Bonneville was the first year for unit construction. Up until this point, every Triumph 650 twin utilized non-unit construction, which meant that the engine, gearbox and primary chain case were all separate components held together by a system of brackets. Unit construction melded all three components into one unitized casing, hence the name. It not only gave the engines a more modern look, the new unit-construction engine was smaller, lighter, stronger, quieter, leaked less oil, was easier to manufacture and to maintain and repair. Triumph started the conversion to unit-construction back in 1957 with the Triumph Twenty One which was Triumph’s smallest twin. The Triumph 5T Speed Twin followed in 1959. Until this point, all of Triumph’s twins shared basic architecture. In other words, the 350 twin used the same crankcases and many other components as the 500 and 650 twins. But during the conversion to unit-construction, Triumph split their twin-cylinder machines into two engine families. The 350 and 500 twins shared architecture, but were completely different than the 650 twins.

LEFT: The non-unit construction Triumph 650 twin (1950-1962).

RIGHT: The unit-construction Triumph 650 twin (1963-1983).

The 1963 Triumph Bonneville was the culmination of a long line of Triumph vertical twins, starting with the 500cc 1938 Speed Twin. Designed by genius Edward Turner, it was the world’s first ‘modern’ vertical twin. It took the British motorcycle industry and the entire motorcycle market by storm and every other brand wanted one for themselves. But before they could do anything about it, Triumph did it again. One year after the launch of the game-changing Speed Twin, Triumph hot rodded their new twin and created a high-performance version of the bike called the Triumph T100 Tiger in 1939. World War 2 came along and put everything one hold until 1946, but when civilian production ramped back up Triumph was back in front and leading the way.

The 1963 Triumph Bonneville was gorgeous to look at, and just as much fun to ride!

By 1949, five competing brands, BSA, Ariel, Norton, Matchless/AJS and Royal Enfield, fielded their own 500cc vertical twins. No sooner than they got caught up, Triumph upped the ante again by boring and stroking its 500 twin out to 649cc and introduced it as the 1950 Triumph 6T Thunderbird Again, the industry was stunned, and once they recovered, once again put their noses to the grindstone to try to catch up. As all five punched out their own 500 twins, some built 600cc twin, some 650cc, and Royal Enfield even out-trumped Triumph with their 700cc Super Meteor. It didn’t help, Triumph just continued to forge new ground and lead the market in innovation and sales. In 1954 Triumph gave their new 650 twin the ‘Tiger-treatment’, ie: hotter cams, higher compression ratio and a bigger carburetor for more power. The result was the 1954 Triumph T110 Tigerand it was hot! Two years later, Triumph developed a new aluminum “Delta Head” that not only added more power but enhanced engine cooling. With it, a new bike was born, the 1956 TR6.

Unit construction made for a much neater engine package, introduced in the 1963 Triumph Bonneville and TR6.

Triumph Bonneville is Born

Up until this point, all these vertical twins, from all six brands producing them now, had used only one carburetor to feed both cylinders. This was made possible by the even firing pulses of the vertical twin, thanks to its 360-degree crankshaft. One carb worked well and kept things simple, and cheap. There is a saying in the motorcycle business that goes: “Too much is never enough.” Hence, if one carb is good, two would be better. Today putting two carbs on a twin-cylinder engine seems like an obvious improvement to make, but in 1959 it was revolutionary. Triumph reworked the Delta Head to accommodate two carbs, by splaying the intake ports outward instead of closer together and parallel as they were on the TR6. The result was the 1959 Triumph Bonneville.

This engine is from a 1963 Triumph Bonneville T120C, sort of the off-road version, hence the high pipes.

1963 Triumph Bonneville Engine 

Once again, the Triumph Bonneville took the world by storm and Triumphwasted no time in setting several top speed records with the new bike, justifying the slogan “The Best Motorcycle in the World”, and until the Norton Atlas came out in 1962, the “Bonnie” was probably the fastest bike that money could buy. But once again, Triumph was ahead of the pack with their 650 twins’ conversion to unit construction. Norton and all the other manufacturers who built vertical twins were still stuck with non-unit engine packages and by this time, few had the money to do anything about it. The exception was BSA, who owned Triumph, and was also the largest motorcycle manufacturer on the planet going in the 1960s. They certainly had the money and so they too made the conversion of their 650 line to unit construction in 1963. The new unit construction engine had been completely redesigned, and while it followed the design of the non-unit engines, virtually no internal components were interchangeable between the two. The crankshaft, rods, pistons, cylinders, head, cams, timing gears, primary drive and oil pump were all new, albeit incredibly similar.

The 1963 Triumph Bonneville got a whole new frame, and a good one at that.  Triumphs from this era were known for their fine handling.

1963 Triumph Bonneville Frame

But the 1963 Triumph Bonneville got more than a new engine, everything else got redesigned also. A new single down tube frame was introduced that stayed in service through the 1970 model year, until it was replaced by the oil-bearing frames of 1971. It was not truly state-of-the-art back in 1963, that title would be taken up by Norton's iconic 'Featherbed Frame' with it's welded steel construction. The new frame used brazed lugs to hold it together, an ancient practice that goes all the way back to the steam era. It worked, but it was heavy and not nearly as rigid as a welded frame. The 1963 Triumph Bonneville also got new bodywork, a new seat and much of the running gear. Brakes, forks and fenders remained more or less unchanged, but the front rim went from 18-inches to 19. Overall it was a handsome machine that worked well and was well-received by the market. In 1963 all was right with Triumph, however storm clouds were gathering and the winds were building, blowing in from Japan. At this time, the Japanese were building small, lightweight bikes, few above 250cc and most, other than Honda, were 2-strokes. But that would all change in 1965 when Honda introduced it’s own game-changer, the 450cc twin-cylinder ‘Black Bomber’. It was very sophisticated engineering-wise, compared to the ancient British machines. The Honda had DOHC (dual overhead cams), a die cast aluminum engine, a 5-speed gearbox, a twin leading shoe (TLS) front brake and an electric starter. And they didn’t leak oil, and the lights always worked! It made 45 hp which was about what the 650cc 1963 Triumph Bonneville made (46hp actually). That would be the first volley in a lopsided war that Britain couldn’t possibly win.

The 1963 Trumph Bonneville came in two flavors: The T120R (for Roadster), and the T120C (for Competition).  Most T120C's came with lights and were street legal.  This one is stripped down for desert racing.  Note the high side pipes and no mufflers.

1963 Triumph Bonneville Specifications

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Triumph Bonneville Books

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More Triumph Bonneville Pages

1959 T120 Bonneville

1960 T120 Bonneville

1961 T120 Bonneville

1962 T120 Bonneville

1963 T120 Bonneville

1964 T120 Bonneville

1965 T120 Bonneville

1966 T120 Bonneville

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1970 T120 Bonneville

1971 T120 Bonneville

1972 T120 Bonneville

1973 T140 Bonneville

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1975 T140 Bonneville

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1977 T140J Silver Jubilee

1978 T140 Bonneville

1979 T140 Bonneville

1980 T140 Bonneville

1981 T140 Bonneville

1982 T140 Bonneville

1983 T140 Bonneville

1983 TSS Bonneville

1983 TSX Bonneville

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