Douglas Motorcycles

Today in Motorcycle History

Douglas SW 348cc 1925

ENGINE. -Vibrationless horizontally-opposed twin-cylinder. Bore 60.8 mm.X 60 mm. stroke, giving 348 c.c.

CRANK CASE - Neat aluminium casting, with polished exterior to facilitate cleaning. All threads and bearing housings supported in in cast brass rings and bushes.

CYLINDERS - Fine iron castings.

VALVES - Made of specially forged 18 per cent, tungsten.

PISTONS - Special crucible cast iron of 18 tons tensile, with two narrow rings at the top.

CRANKSHAFT - A solid steel stamping machined all over and ground, running in two heavy duly ball bearings of robust dimensions.

MAGNETO - E.I.C., or other first-class British make.

CARBURETTER - Douglas, Amac or Binks according to supplies.

LUBRICATION - Semi-automatic—a spring returned hand pump set in the tank at a convenient angle for working forces oil through the needle valve in the sight feed to the front cylinder. From here the oil passes to wells in the crank case, into which the big ends dip and distribute oil to the rear cylinder.

COUNTERSHAFT UNIT - Douglas indestructible two-speed gear box. Pinions 5 per cent, nickel steel of the constant mesh type, the drive being engaged by sturdy sliding dogs. Gear ratios : 6 and 9 3/8 (approx.). Fitted with Douglas kick-starter.

TRANSMISSION - Engine to gear box by 5/8in x 1/4in chain gear box to rear wheel 3/4in. belt. Belt slip and belt troubles are unknown, due to the even torque of the opposed twin engine and large pulley diameters.

In 1922, Douglas won the Australian Six Days Trial and repeated this success in 1923 and 1924.

CLUTCH - Douglas single plate incorporated in the flywheel, of extremely smooth action and light operation,

BRAKES - Powerful shoe operating in "V" of belt rim, provided with spring compensating mechanism, and operated by conveniently placed toe pedal on right-hand side. Front - special design hand-operated rim brake.

FRAME - Of highest grade butted weldlcss steel tubing. Lugs machined from solid steel stampings. All lugs for generator, tool Lags, etc., arc brazed on solid and part of the frame design.

SPRING FORKS - Exceptionally well-designed giving wide movement and big clearances, The side plates move in unison and so keep the fork sides in perfect alignment. The hollow spindles carry an ample supply of lubricant and large greasing caps.

FOOTBOARDS - Cast aluminium with heavy rubber studs preventing clatter on rough surfaces, providing a firm grip and absolute comfort.

HANDLEBARS - The Douglas new flat touring shape gives an upright riding position with a natural wrist angle and hand grip.

MUDGUARDS - For 1925 are an interesting feature - strong and wide giving ample protection.

CARRIER - A rigid tubular construction neatly housing two metal covered tool bags.

TANK - Sturdily built. Extra large filler caps - drain cock - petrol litter to main supply - capacity, 1 1/4 gals, petrol ; 3 pints oil,

SADDLE - Douglas patent pan seat insulated from shock by a sprung nose and at the rear by large diameter coil
springs - exceedingly low and comfortable.

TYRES - 26 x 2 1/4 in., first-class make.

HUBS - Adjusting type, solid axle and cones, oil retaining, dirt and waterproof.

CONSUMPTION - Oil, 1,0000 m.p.g.; petrol 90 m.p.g.

Overall length, 7ft. lin. Overall width of handlebars, 2ft. 8in. Average weight, 192 lbs. This applies only to U.K.

We reserve the right to alter or amend this specification without previous notice.

Price in U.K. - £42 : 0 : 0

Douglas was the first motor cycle to capture the whole class of records

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