A very rare model with lots of history.

Developed around a 499cc single-cylinder four overhead valve four-stroke commissioned by Triumph from engine expert Ricardo, the Triumph Ricardo was a replacement for the ageing Triumph side-valves. Ricardo produced a number of prototypes aimed at reducing thermal stress on the inadequate valve materials available, while improving airflow through increased valve area. Harry Ricardo's final design had the four valves operated by the existing tappet mechanism and set a new standard for the power output possible from a 500cc single-cylinder engine, achieving over 20 bhp - the same as a 1500cc car engine of the time!

Capable of 70 mph, the four-valve head allowed more efficient gas flow and the spark plug could be positioned in the middle for optimum combustion. Each pair of valves was parallel, at 90 degrees to each other, with the valve stems and springs exposed, as were the long pushrods which ran on the outside of the engine. A light alloy piston ran in a steel cylinder barrel and the cylinder head was made of cast iron. The rest of the cycle parts were based on Triumph's well proven Triumph Model H side-valve. This had a poor reputation for handling and was not really built for the more powerful four valve engine. On later models the oil system (which had relied on a manual hand pump) was replaced with an external oil pump. The 'Riccy' continued in production as a sports model until 1928.

Please phone for more information.