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Triumph Ricardo

1924 Triumph Ricardo1921 Triumph Ricardo

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Having established an enviable reputation in the early days of motorcycle competition, Triumph chose to ignore events such as the Isle of Man TT for several years. So when they performed an abrupt about turn in 1922 it could be expected that they were pretty confident of the bike they chose to enter - the super sports Triumph Ricardo.

Sir Henry (Harry) Ricardo was a renowned combustion expert who had worked on behalf of many companies when he was asked by Triumph to advise on a replacement for their trusty side-valves. Ricardo produced a number of alternatives before Triumph announced that their new overhead-valve model would use a four-valve head design. In fact, from the cylinder barrel down, the rest of the bike was virtually identical to Triumph's tried-and-tested Model H side-valve.

The theoretical advantages of a four-valve head were numerous. Gas flow could be more efficient, the spark plug could be positioned centrally for more efficient combustion and lighter components would respond quicker, allowing higher revs. In fact, Ricardo's design was quite conservative, using small ports and unusually recessed valves. Each pair of valves was parallel, set at 90 degrees to each other, with stems and springs exposed; the piston, which was of light alloy, had a concave crown and a slipper-type skirt. The cylinder barrel was made of solid steel and had deep finning, while the head, which had two parallel exhaust ports, was iron.

From there down, the engine was based on the Model H. The flywheels were slightly smaller, to allow free revving, while lubrication, relying on constant-loss fed by hand pump, was later changed to dry sump fed by external oil pump. The resulting Model R Fast Roadster was marketed as a fully equipped sports model and attracted favourable reports. In this form, it lapped Brooklands at 68mph, while a racing version also took the hour record at almost 77mph and a flying mile at nearly 84mph.

Three were entered for the 1921 TT but handling deficiencies meant that only one finished. A year later, the Triumph Ricardo was back with the new lubrication system, stronger valve gear, a modified cylinder with new dimensions and made of cast iron, a three-speed gearbox and new front fork. This time it finished second in the TT and the following year went on to take a number of continental wins and gold medals in the ISDT.

After 1924, Triumph switched their development efforts to a new model, although the 'Riccy' stayed in their range as a sports model until 1928. But the four-valve layout had proved its potential for the future.

Triumph Ricardo

  • Years in production - 1921-28
  • Engine - single-cylinder four-valve ohv four-stroke
  • Bore and Stroke - 80.5 x 98mm
  • Capacity - 499cc
  • Power - 20bhp @ 4600rpm
  • Carburettor - Triumph twin barrel
  • Tyres (front/rear) - 3 x 26in/3 x 26in
  • Transmission - Triumph three-speed gearbox
  • Weight - 250lb
  • Top speed - 70mph