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British Motorcycles

Duzmo 496cc OHV Single 1923


Duzmo-1923-Motorcycle.jpg
Duzmo 1923

A low saddle position and a compact layout are features of the 1923 Duzmo.

SOLO SINGLE FOR COMPETITION RIDING.

496 c.c. Duzmo with Inclined o.h.v. Engine and Close-ratio Gears.

FOR fast touring, competition work, or for use with a light sidecar the clos« ratio Duzmo is eminently suitable. Naturally, if employed for passenger work a different set of gear ratios would be required.

Fitted with a 496 c.c. engine (89x79 c.c.) tilted slightly in the frame, which is substantially constructed but of quite conventional design, and a three-speed close ratio Sturmey-Archer gear box, the machine has a pleasing and businesslike appearance.

Overhead Valves in Detachable Head.

The actual model illustrated is the latest pattern, but owing to its having been prepared for Brooklands it differs from the standard model in one or two details, to which reference will be made later.

Overhead valves are fitted which are situated in the detachable head and are inclined to the extent of 30°. Machined all over internally, the head- is semi- spherical and a very clean piece of work, as not only is its interior dead smooth and arranged so as to give a clear pas- sage to the inlet and exhaust gases (1 1/4in. is the diameter of the exhaust outlet), but the exterior is heavily and scientifically finned, while an air passage is left beneath the top fin which bridges between the two valves.

Double Valve Springs.

Each valve is provided with two springs, while the rockers, mounted on brackets which are practically extensions of the , holding-down bolts, have large bearing surfaces, and screw-down grease caps to ensure long life ; they are kept up to their work by light return springs.

There are two sparking plug holes in the head, in one of which a fir cone radiator is fitted.

Other interesting engine parts are the aluminium piston, which has one deep ring, and the connecting rod, which is machined all over, is drilled for lightness and has a roller bearing big end ; the gudgeon pin is fin. in diameter, and Skefko self-aligning bearings are provided for the main shaft. Another important alteration is the increase of clearance between flywheels and crank case, which reduces oil friction.

Foot-operated Oil Pump.

While the model illustrated is fitted with a foot-operated oil pump delivering the lubricant through a drip feed, a Best mechanical lubricator is supplied to the standard model.

Binks rat-trap carburetters are fitted to all models.

The usual brake equipment is a Webb front brake and a rear pulley rim brake actuated by a direct pull pedal, but a Webb rear brake may be had.

Brampton forks are supplied but modified by means of rubber blocks to the top springs, so as to stop " dithering " at high speeds.

In the machine illustrated it would appear that the silencing arrangements would be inadequate, and would invite the attentions of the police, but the standard model is provided with a silencer fitted to the end of the long exhaust pipe which is quite effective and causes no appreciable loss of power through back pressure.

The following particulars and dimensions will be of interest : Price, £100 ; weight, 220 lb. ; wheelbase, 54 1/2 in., ground clearance, 4 1/2 in. ; and tank capacity, two gallons of petrol and half a gallon of oil.

Well thought out and bearing the mark of being designed by a practical rider, the new model Duzmo deserves popularity. John Wallace, Cedar Road Works, Enfield Highway, is the maker.

Sources: The Motor Cycle




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