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Douglas Motorcycles

Douglas 1925 OB 600cc


The OB/25 model has been designed as a dual purpose mount, combining high speed with reliability, and a positively wonderful power output from a vibrationless, twin-cylinder opposed, overhead-valve engine,

Every machine is given an exhaustive road test before delivery.

As a sidecar outfit, this machine leaves nothing to he desired. The speed and acceleration make the machine a pleasure to handle, and its hill climbing capabilities are revolutionary. The comfort of the driver has been very care fully studied, and in conjunction with the special patented spring saddle, aluminium rubber studded footboards and a large combined leg- and under-shield, the machine can be ridden in wet, muddy weather with a degree of comfort that cannot be experienced on any other machine.

The power unit has been developed from experience gained in producing the 600 c.c. DOUGLAS machine, which won the 1923 Sidecar T.T. Race, and, combined with our vast road experience, has enabled us to offer the most fascinating machine for both sidecar or solo work that has ever been produced.

ENGINE - 68 mm. x 82 mm., capacity 596 c.c. Deep ribbed cast-iron cylinder barrels fitted with detachable cylinder heads and unbreakable overhead valves. The cylinder heads  carry a special device for lubricating the overhead rockers. The valves are fitted with double valve springs.

PISTON -  The pistons are of special cast iron, having a tensile strength of 18 tons.

CONNECTING RODS - Of special alloy steel, H section, the big end being hardened and ground to take the roller bearings, the little end being fitted with a gun-metal bush.

CRANKSHAFT - Of special alloy steel, hardened and ground, fitted with roller hearings of the cage type. The crankshaft is very short end stocky, which thus eliminates all tendency to whip.

CAMSHAFT - Of special alloy steel, ground to give a valve timing that has been found extraordinarily efficient for touring and high speed purposes.

INDUCTION PIPE - Is fitted with a large exhaust heated jacket.

Douglas finished first in the 1923 Sidecar T.T. and made fastest time in the 1924 Sidecar T.T.

KICK-STARTER -  lncorporated in the timing cheat of the engine.

CARBURETTER - Amac or Douglas semi-automatic type, according to supplies.

IGNITION - By E.I.C. or other British make of magneto. K.L.G. sparking plugs are fitted to this machine.

LUBRICATION - Semi-automatic by spring returned hand pump, through adjustable sight feed fitted on petrol tank, the oil passing through to the front cylinder, after which
lubrication is automatic. We recommend for this machine WAKEFIELD S Castrol X.L.

GEAR BOX - Douglas patented, three-speed special oil retaining gear box is used, having short, large diameter shafts and heavy-duty hall hearings,

CLUTCH - Douglas, inherently balanced, single plate flywheel clutch is fitted, hand control.

FRONT FORKS - Of special pattern fitted with one piece links giving great rigidity. Lubrication of the forks is by means of pressure grease gun system.

FRAME - Of new duplex Douglas design and built of weldless steel tubing, giving a very low centre of gravity and riding position, making the machine practically immune
from skidding.

PETROL TANK - Of large capacity, holding approximately 2 1/2 gallons and 1/2 gallon of oil.

SADDLE - Douglas patent saddle, giving a low riding position and insulating the driver from all road shocks.

TYRES - 700 x 80 first-class make.

FOOTBOARDS - Cast aluminium with heavy rubber studs preventing foot chatter.

MUDGUARDS - Strong, deep section giving ample clearance.

BRAKES - Both front and back brakes are fitted with "V" shoes operating in special brake drums.

FINISH - Tank is highly burnished in aluminium with royal blue panels. All enamelled parts are treated by anti-rust process and afterwards are enamelled three coats of the
finest black.

STANDARD EQUIPMENT - Complete kit of tools, pump, grease or oil gun.

CONSUMPTION - Oil. 1,000 m.p.g. Petrol. 75-80 m.p.g.

Electrical equipment for this model £10 extra.

Acetylene lighting which includes head lamp, generator, lamp brackets, etc., also horn, 30/- extra.

Net Weight. Solo, 243 lbs, Sidecar outfit. 416 lbs,

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

Price in U.K. - £70 Solo. £92 Sidecar Outfit.

Douglas won the Welsh T.T, 1923, running the rest of the field to destruction.



If you have a query about Douglas 1925 OB 600cc, or have some information to add about these vintage British machines, please contact us
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