The water cooled Lewis motor

Lewis are probably best remembered for their water-cooled motorcycles, which were built in a variety of forms between 1905 and the very early 1920s. The water cooled era at Lewis began in early 1905 with experiments using water-cooled De Dion Bouton motors. Later that year Vivian Lewis and T.P. O'Grady lodged an Australian patent (4275/1905) for An improved method of and means for cooling the cylinders of motor bicycles, in which they laid out their ideas for a water cooled motorcycle.

There has been much conjecture about the origin of the motors used for the water-cooled machines. At this stage, the origin of the earliest machines (with atmospheric inlet valves) is still uncertain, and although Lewis lore might suggest Blumfield origin, I think we might in time find a link with the Stevens Motor Manufacturing Company who were responsible for the 1907-on 3 h.p. side-valve motor. From 1911 (or possibly late 1910), engines were sourced from F.E. Baker (Precision).

As I rebuilt my c1908 water-cooled motor, I developed a scepticism that such a motor could have been built by a UK manufacturer. There is an element of "roughness" about the original build of the motor that is more in line with local manufacture, but given the parlous state of Stevens at the time it could just be an example of production under less than optimal conditions. Although unlikely, we should probably leave open the possibility that the Lewis motors were copies of the Stevens engine.

Note that the "Lewis" badge seen on the crank case of most Lewis motors is riveted on (almost invisibly) for all the pre-1911 motors. "Lewis" is cast in to the timing covers of the Precision engines, and into magneto chain cases when present.

3 1/2 h.p. de Dion water cooled motor

In March 1905, Lewis exhibited a pair of water-cooled motorcycles, "the first constructed in this state".
One used a 3 1/2 h.p. De Dion Bouton motor (most likely similar to the one shown here) and the other a 3 h.p. motor from the same manufacturer. These two machines should be considered the forerunners to the long line of Lewis water-cooled motorcycles. It is not known how many De Dion-engined machines were built. Does anyone have an illustration of these early Lewis machines?

Early water cooled Lewis motorcycle

In September 1905, it was reported that the Lewis Motor Works had just finished a 2 1/2 h.p. water-cooled motorcycle "the engine of which was made on the premises". Shown is the motor of the water-cooled Lewis once owned by N. Jackson. This machine used the early-style radiator with curved corners and hot water inlet from the rear. Note the absence of writing on the motor. The exhaust lift lever pivots at the rear of the cylinder, providing a rather tortured path for the exhaust-lift rod. If this is not the prototype water-cooled Lewis, it is certainly a very early example, c1905. This or a similar machine was snapped in the white garage.

1906 Lewis water cooled motorcycle

A production engine, c1906. Other than the Lewis plate on the crank case, the inscription on the magneto chain cover (LEWIS MOTOR TYPE, 5,W ADELAIDE S.A.), and the reversal of the exhaust lift arm, not too much seems to have changed from the model above. This machine is featured as photograph 09 in the Lewis Album, and similar machines are seen in the white garage. The manufacturer of the motor is still an open question.

1909 Lewis water cooled motorcycle

The first of the side-valve motors appeared in 1907, although this illustration is from the 1909 catalogue. This motor was a product of the Stevens Motor Manufacturing Company. At some point in the evolution of this motor, both the inlet and exhaust ports grew is size. On the later motors, the exhaust exit was a little closer to the horizontal. A key identifier for this motor is the somewhat heart-shaped timing chest, whose cover was bronze on the earliest models, but later became either aluminium, or, in at least one case, steel.

Unknown Lewis motor cycle

A mystery motor, characterised by the "U" shaped timing chest and a water drain cock on the front of the water jacket behind the exhaust pipe. The cylinder casting and valve lifter detail are strikingly similar to the Stevens engine. At a guess, the date would be c1910, just before the introduction of the Precision motor.

1912 water cooled Lewis motorcycle

On the first of the water-cooled Precision motors, the hot water outlet was screwed into the water jacket between the valves. Aside from the steep angle of the exhaust port, there are many similarities between the first "Precision" cylinders and those of  earlier Stevens models. This is the 3 1/2 h.p. motor as shown in the 1912 Lewis catalogue. By 1914 (see below), the outlet had moved to in front of the exhaust valve. The rather absurd Brown & Barlow carburettor was introduced c1912 for the Lewis model with the fuel tank behind the seat tube.

3 h.p. Lewis water cooled Precision

The 1910-on Precision motor was offered in two sizes: this is the smaller of the two as it appear in 1914. Sometimes referred to as the "narrow valve" Precision, it had bore and stroke of 75 x 86 mm giving 380 cc, and was rated at 3 h.p. The illustration is from the 1914 Lewis catalogue, but seems to date from a year or two earlier. That said, there were relatively few changes during the late-1910 - c1916 production life of the motors.

3 1/2 h.p. Lewis water cooled Precision

The larger Precision motor
(85 x 88 mm giving 499 cc, rated at 3 1/2 h.p.) was offered in parallel with the 3 h.p. Naturally enough, it is sometimes referred to as the "wide valve" motor. The illustration is from the 1914 Lewis catalogue. Changes from the earlier version were few, but included repositioning the water outlet to in front of the exhaust valve (where the manifold was mounted to a flange), and a rounding of the bottom of the timing chest.

3 1/2 h.p. Green Precision water cooled motor

A photograph survives of a Lewis machine, stripped for racing, fitted with the water-cooled Green Precision motor. The year of manufacture is not known, but is likely to be c1914. The illustration here comes from a war time edition of Motorcycles and How to Manage Them, as no record of this motor has yet been found in Lewis literature.

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