Sunbeam Motorcycle
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The Marston Sunbeam Club & Register

The V Twins 6HP, 8HP, JAP, AKD , MAG, 1913-1923

After the success of the 2¾HP, JML quickly realised that they needed a machine with the power to haul a sidecar so, in June 1913, they announced the 6HP. Powered by a JAP engine of 770cc, this model was fitted with Druid forks, a rear-mounted magneto, and balloon tyres. Not trusting anyone else’s workmanship, the craftsmen at Sunbeamland, it is said, stripped each engine on receipt from Tottenham to make sure it was up to Sunbeam standards! This model was the first to be fitted with Marston’s three-speed sliding pinion gearbox.

6 HP Jap

The JAP-engined model continued in 1914, but 1915 saw a change of engine, to the 798cc Abingdon King Dick (AKD). This model also saw the introduction of the rack-and-pinion controlled constant mesh gearbox, and the first internal-expanding drum brake ever fitted to a Sunbeam. The bicycle type stirrup brake continued at the front, however. Brampton Biflex forks were fitted, and full Lucas electric lighting was available

6HP AKD Vtwin

There was a further engine change in 1916, this time to the 8 HP, 996cc oie MAG unit. The height of this engine meant that there was very little ground clearance, and the model was used almost exclusively for sidecar work. Most were supplied to the Russian army, and fewer than a handful survive. The military machines were equipped with a three-compartment tank: oil, petrol and paraffin.

 

8HP Mag VTwin

1917 saw two new versions of the V-twins. The first, exclusively for Russia, was a 5 HP JAP-powered machine of 654cc, intended for solo use as the standard 3½ HP model was not considered powerful enough for the Russian army.

1917 5 HP SUNBEAM-JAP in its hayday

1917 5 HP SUNBEAM-JAP in its hayday

The second version, which continued until the end of V-twin production, was powered by the 8 HP JAP engine of 996cc. A small number were sold to the military as stretcher-carrying outfits, but there is no evidence they actually saw action.

8 HP Vtwin Military

 

After the end of the war, many of the 8HP twins found their way onto the civilian market, but when production re-commenced in 1919, the JAP-powered 8HP was again featured, with very little change. The 1920 catalogue shows the 8 HP, still with the 996cc JAP engine, but now with the Marston patented leaf-spring front fork. The price was a massive 176 guineas, almost double the price of the MAG-engined version only five years earlier!

8HP JAP V Twin

The 8 HP continued until in 1923, with the price down to 135 guineas and the machines being assembled only to order from stock parts from previous years, the V-twins were finally phased out.

8HP 1923

A beautifully Restored 8hp Mag Engine Vtwin

Restored Vtwin

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