Bike India : 2020-06-10

DOUGLAS DRAGONFLY : 55 : 55

DOUGLAS DRAGONFLY

Specificat­ion DOUGLAS DRAGONFLY (1955) Configurat­ion: Valve-train: Displaceme­nt: Bore x Stroke: Compressio­n Ratio: Electrics: Fuelling: Air-cooled flat twin OHV pushrod 348 cc 60.8 x 60 mm 7.25:1 approx 6V battery; coil ignition 1.125-inch Amal monoblock carburetto­r Front suspension developed by Ernest Earles was also seen on BMWs and MV Agustas of the time 348-cc flat twin started life in a generator, but was greatlyref­ined for the Dragonfly Maximum Power: Clutch: Transmissi­on: 17 hp @ 5,500 rpm Four-speed, chain final drive Five-speed Chassis Frame: Front Suspension: Tubular steel cradle Earles forks, adjustable preload Rear Suspension: Twin shock-absorbers, adjustable preload 178-mm SLS drum 178-mm SLS drum 19-inch, wire-spoked 3.25-19 Avon Roadrunner 3.50-19 Avon Roadrunner 1,435 mm 762 mm 24 litres 166 kg (dry) Front Brake: Rear Brake: Wheels (F/R): Front Tyre: Rear Tyre: Wheelbase: Seat Height: Tank Capacity: Weight: Simple instrument­ation was all one needed back then Headlight nacelle flows smoothly into the fuel tank and uprated lubricatio­n system. Like the T35, the Dragonfly used chain final drive rather than a BMW-style shaft. Because the crankshaft was in line with the bike, this required a bevel-gear system between the four-speed gearbox and the front sprocket to turn the drive through 90 degrees. The rectifier and coil were located under the large petrol tank; other electrical components lived on top of the engine, under an alloy plate that helped give the powerplant a notably smooth look. The twin-downtube frame and the front suspension were built by chassis specialist Reynolds. The front suspension system, as fitted to BMWs, was the pivoted, twin-shock system designed by Ernie Earles, who had also styled the Dragonfly’s nacelle. At the rear, twin shocks replaced Douglas’ previous torsion bar suspension system and were a sophistica­ted feature at the time. At 166 kg dry the Dragonfly was slightly heavier than the T35 MkV, but was respectabl­y light given its sturdy chassis. This very clean, restored 1955-model machine felt reasonably manoeuvrab­le once I’d managed to haul it off its hard-to-use centre-stand. The way the nacelle remained in position when I turned the bars seemed slightly strange at first, but in most respects the Douglas was normal and well-behaved. Its motor started easily enough, given a fairly light kick of the starter lever, and didn’t seem particular­ly noisy despite the model’s reputation for rattling. That was an indication that this recently rebuilt engine was in good condition and the Douglas ran well throughout my ride. There was a fair bit of noise when I got under way, though; mostly a not receiversh­ip later that year. Although production continued, expenditur­e was severely restricted and there was little chance of a full recovery. Some racing and developmen­t work continued, under the control of former race ace Freddie Dixon. In 1950 the firm introduced two sporty versions of the T35, the 80 Plus and 90 Plus, named after their claimed top speeds of 80 mph (129 km/h) and 90 mph (145 km/h). Engine changes for both included new cylinder-heads, extra cooling fins, and a strengthen­ed crankshaft. In addition, the 90 Plus had higher compressio­n ratio and each motor was dyno-tested to confirm it produced at least 25 hp. The 90 Plus just about lived up to its name, which meant it performed pretty well, but Douglas continued to struggle in the early 1950s. Hopes were boosted in 1954 with the unveiling of the Dragonfly, which combined a new chassis with a modified version of the 348cc engine. When launched at that year’s London show at Earls Court, the model made quite an impact, largely due to its striking styling with its headlamp nacelle blending into the petrol-tank. The sheet steel nacelle held the speedomete­r, a smaller ammeter, and the ignition switch as well as the headlamp. The new engine retained the traditiona­l T35 capacity of 348 cc from near-square dimensions of 60.8 x 60 millimetre­s, but was influenced both by the 90 Plus and a 500-cc prototype that had been developed and then abandoned a few years earlier. Its cylinder-heads were based on those of the 500, while the bottomend was strengthen­ed in 90 Plus style with stronger crankcase webs 55 www.bikeindia.in June 2020 Bike India

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