Perhaps one of the most interesting designs in motor cycles to-day is the 1934 500 c.c., o.h.v. Model 9 Sunbeam, which was subjected to a severe test last week. So far as performance and general handling is concerned, this model was a revelation. At all speeds it proved exceptionally light and steady; in fact; the steering damper was hardly necessary, even at high speeds.
Into every Sunbeam is built the knowledge gained in years of continuous manufacture. The new gearbox, with its ratios carefully chosen for acceleration, combines smoothness and silence with ease of operation.
The Sunbeam oil bath transmission with patent cush drive ensures engine power being delivered to road wheels smoothly, and adds to the life of all bearings.
Immense Appearance.
In appearance, the Sunbeam gives an impression of immense solidness and compactness. In the finished job of resplendent black and gold, good workmanship is the feature. After adjusting the foot rest to suit the rider, a comfortable riding position was secured. An incorrect carburetter setting necessitated several "kicks" before the engine "ticked over." A slow and even "purr" was heard, with the exhaust note well modified in pitch. For an o.h.v. engine of this type, mechanical silence was reasonably good, although with a cold engine the o.h.v. gear could be heard at times.
Excellent Manners.
During the test the machine behaved excellently. In the muddy sections the rider felt at home with the cycle. It was absolutely steady and could be steered just where the rider wished. Fault could not be found with road-holding, and, even under extreme conditions, the rear wheel remained glued to the road. The steadiness of the steering, whether on corners or in sand or gravel, gave a rider a feeling of absolute security. A steering damper was fitted, but the need for its use was unnecessary.
Easy Riding.
A speed of 18 m.p.h. in top gear was attained without "snatch," and at this speed the throttle could be opened up suddenly and the mount would glide away effortlessly without any feeling of harshness from the transmission. The maximum speed was 79 m.p.h., but the throttle was not opened further owing to the motor being new. The brakes would bring the machine to a quick standstill with smoothness that could not be improved upon. No matter how suddenly they were applied, they were exceptionally smooth, and there was not the slightest trace of wheel lock.
A Joy to Operate.
The gearbox was a joy to operate. The change itself, no matter the road speed or ratio required, could be selected with sureness and silence. Through city running the third gear was used, and all hills were ascended in top without effort. Though the gears were hand operated, the rider considered that a foot change would be a decided advantage. The clutch was extremely light, but being a little out of adjustment a clutch spin caused noise on stops when putting in low gear. When travelling at night the head lamp gave an excellent light, showing the road in a penetrating beam that made night riding a pleasure.
At the completion of the test a check was made up of the petrol and oil consumed. Petrol averaged 78 miles a gallon, and the oil used was almost nil. Considering that the Sunbeam was just out of the case and had not been run in, the performance was most creditable.
Specifications of the Model 9 Sunbeam
Engine.—Sunbeam single cylinder two-port O.H.V. detachable head. Enclosed rocker gear, push rods and valve stems lubricated automatically under pressure. Double coil springs for valves. Tappet adjustment direct to stem of valve. Adjustable dry sump lubrication with oil gauge on tank. Amal carburetter with twist grip control.
Ignition.—Lucas magneto.
Gearbox. —Silent constant-mesh 4-speed with enclosed kickstarter. Filler and oil level plug provided. Self-aligning, with drawbolt adjustment.
Gear Ratios. —Standard solo: 4.6 to 1, 6.1 to 1, 8.8 to 1, 13.8 to 1. Sidecar: 5.3 to 1, 7 to 1. 10.1 to 1, 15.9 to 1.
Transmission. —Front chain totally enclosed in oil bath chaincase. Rear chain protected by special chainguard and automatically lubricated. Shock absorber on engine shaft. Six-spring sensitive hand-operated clutch.
Wheels.—Detachable and interchangeable. Hubs fitted with grease gun system. Frame. — Low riding position with saddle tank and separate oil tank. Adjustable handlebars with steering damper. Adjustable rubber-covered footrests. Front and rear low lift stands fitted.
Front Fork. —Central spring and adjustable shock absorber. Lubricated by grease gun system.
Mudguards.—Rear fitted with lifting handle and detachable section permitting easy removal of wheel. Front fitted with deep valances and mudflap.
Brakes. —Large internal expanding in both wheels with quick hand adjustment. Both brakes remain in position when wheels are removed.
Measurements. —Bore : 80 mm. Stroke : 98 mm. Cylinder capacity: 493 cc. Petrol capacity: 2 ½ gallons. Oil capacity: 4 pints.
Victorian Distributors. —Messrs. Findlay and O'Connor, 320 Elizabeth street and 299 Swanston street, Melbourne.
September 15th 1934
Australian Cycling & Motor Cycling, September 15th 1934. Trove NLA
Further information: Sunbeam Model 9 1924-1937
