General Specification
The specification below gives full details of the latest models of the famous A.J.S. Twin, which is available in English and Export forms as illustrated on pages 20 and 21 of this catalogue.
The English Model 38/2 is fitted with semi-sports handlebars, footrests, foot gear-change, and hand clutch control.
The Export Model 38/2A is fitted with upturned handlebars, rubber-covered footboards, left-hand gear change and foot clutch control.
ENGINE. A.J.S. high efficiency 50-degree twin cylinder 9.9 h.p. engine, with super-power detachable cylinder heads, and air-flow cylinders incorporating dwarf tappet chests with valve springs carried in insulated steel thimbles, preventing the transmission of heat from the engine to the valve springs. Anti-slap lightweight "Lo-ex" alloy pistons. Improved roller bearing big-end bearings giving exceptionally long life to this important part. Very stiff crankshaft assembly with crankshaft mounted on two journal ball bearings on driving side and flood lubricated bronze bearing on timing side. Tappets and valve gear totally enclosed and lubricated. Timing gear submerged in oil. Magneto chain running in cast-aluminium case.
Bore, 85.5 mm.; Stroke, 85.5 mm.; Capacity, 990 c.c.
LUBRICATION. Full dry-sump system with pressure-type fabric oil filter, as described on page 2.
GEARBOX. Four-speed pivot-mounted heavyweight gearbox to A.J.S. design. On model 38/2 built-in positive stop footgear change is incorporated. On Model 38/2A gear change is by convenient hand lever on left-hand side of petrol tank.
Model 38/2A can be fitted with gearbox giving three forward speeds and reverse gear at extra charge shown on page 24.
Gear ratios:
CLUTCH. Multi-plate heavy duty large diameter clutch in separate compartment in chaincase to exclude oil from friction faces. Finger operated cable adjuster on Model 38/2 which has clutch control by lever on handlebar. On Model 38/2A clutch controlled by pedal at front end of left-side footboard.
FRAME. Full cradle-type with integral front engine lug. Extra large diameter chain stays and back fork stays. Rear portion of frame of extra width to allow ample clearance for large section tyres. This frame possesses great torsional rigidity and is designed to stand up to the heaviest sidecar loads for commercial or passenger work.
SPRING FORKS. Extra heavy locked-link girder-type forks, with duplex plate friction dampers, controlled by convenient knob on left side. Duplex-plate steering damper controlled by knob above handlebars.
BRAKES. Internal expanding front and rear. Front 7 in. diameter, rear 7 1/4 in. diameter. Front drum fitted with large cooling fins. Improved type high friction brake linings front and rear. Both brakes incorporate dust and water excluders and finger adjustment. Front brake controlled by lever on right handlebar. On Model 38/2 rear brake controlled by long pedal on left side, on Model 38/2A rear brake controlled by ratchet pedal at front end of right-side footboard.
CARBURETTOR. "Amal" semi-automatic two-lever, with twist-grip throttle control and large "Amal" air filter.
REAR CARRIER. Welded tubular steel, with quickly detachable top. Two large pressed steel tool-boxes provided.
TANK. Chromium plated petrol tank with usual A.J.S. black and gold finish. Flush-fitting instrument panel mounted on top of tank containing lighting switch, ammeter, detachable inspection lamp, and provision for clock. Capacity, four gallons three pints. Separate oil tank mounted under saddle with accessible filler-cap. Capacity, five pints.
TRANSMISSION. By chain throughout. Front chain completely enclosed in pressed steel oil-bath chaincase of A.J.S. patent design with combined filling hole and oil level indicator. Rear chain completely protected by new design deep-section chain-guard with front and back panels giving almost complete enclosure. Shock-absorber on engine shaft.
WHEELS. Well-known patent A.J.S. quickly detachable and interchangeable wheels, front and rear. Extra heavy 19 in, x 3 in., 14-gauge rims, with 6-gauge spokes, giving enormous strength. Wheel rims chromium plated with black centres and gold lines.
TYRES. Heavy duty 27 in. x 4 in. cord tyres.
MUDGUARDS. Deeply valanced front mudguard of wide section, with centre rib. Extra wide rear guard with centre rib, with back portion hinged to ensure easy wheel removal.
HANDLEBARS. Model 38/2 fitted with semi-sports handlebars, carried on trailing links, and with adjustable controls. Model 38/2A fitted with long comfortable touring handlebars.
SADDLE. Large pan-seat with three-point suspension and exceptionally long springs at the rear, affording great comfort.
ELECTRICAL EQUIPMENT. Lucas magdyno electric lighting with constant voltage control. Electric horn.
EQUIPMENT. Full kit of tools, grease gun, and tyre inflator. set,
SPECIAL NOTE. Unless specially ordered otherwise, all machines are supplied with speedometers at the extra charge shown on page 24.
PAGE 19
Source: AJS Factory Catalogue 1938
