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Sunbeam Motorcycles

Sunbeam Model 90

The OHV Model 9 was available in 500 and 600cc versions. A sports version was offered for the 1932/33 season in a separate catalogue as the 'TT Replica' Model 90. This was a bit of a stretch as the factory had not fielded a racing team since 1930.

SPECIFICATION

ENGINE.

Sunbeam single cylinder, 493 c.c. racing two-port O.H.V. enclosed rocker gear, push rods and valve guides lubricated automatically under pressure. Sunbeam patent double hairpin valve springs and high compression piston fitted. Tappet adjustment direct to stem of valve. Exhaust valve lifter operated by cable from handlebar. Adjustable dry sump lubrication system (Pat. No. 29041 3) with oil gauge on tank. Sunbeam shock absorber on engine shaft. Special racing double float chamber Amal carburettor with twist grip control. Auxiliary air control. Large exhaust pipes with Sunbeam patent silencers with fishtails.

GEARBOX. Sunbeam four-speed. Close ratio racing gears. Gearbox lubricated through accessible filler. Level plug provided. Draw bolt attachment for adjusting front chain. Sunbeam six-spring hand-operated clutch with Ferodo insets. Foot-operated gear change. Front chain totally enclosed.

GEAR RATIOS. Standard gears 4.6 to 1, 5.6 to 1, 6.7 to 1, 9.6 to 1.

TYRES. Back, Dunlop 26 in. x 3.25 in. wired on. Front, Dunlop 27 in x 2.75 in. wired on. Well fillers fitted to both wheels.

IGNITION. Special racing Lucas magneto.

FRAME. Low riding position with extra large saddle tank and separate oil tank. Sunbeam adjustable sports type handlebars with Sunbeam steering damper. Terry saddle. Large tool bag fitted on left-hand chain stay. Rear mudguard cushion. Adjustable racing type footrests.

PETROL AND OIL TANKS. Fitted with racing type knee grips

WHEELS. Detachable and interchangeable. Brakes remain in place when wheels are removed. Hubs fitted for grease gun lubrication. Wheels are balanced.

MUDGUARDS. Light pattern guards with special stays. Rear guard fitted with lifting handle and hinged rear section to permit removal of back wheel:

FRONT FORK. Sunbeam front fork with central spring and Sunbeam adjustable shock absorber. Lubricated by grease gun system. Front wheel stand.

MEASUREMENTS. Bore: 80 mm. Stroke: 98 mm. Cylinder capacity: 493 c.c. Petrol capacity, 3½ gall. Oil capacity: 6 pt. Compression ratio: 7½ to 1.

SPEEDOMETER. Special speedometer fitted on top of fork girder with enclosed drive inside front brake drum.

Sources: sunbeamsidevalve.com, period literature


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