The original 2¾ h.p. model was supplemented
with a 6 h.p. (770cc) JAP twin cylinder machine in June 1913. A 3½
h.p. (499cc) side-valve model followed in September 1913.
The all-black colour scheme was introduced, with gold leaf lining.
Engine and Gearbox
Unlike the earlier machine, both the 6 h.p. model and 3½
h.p. model had a three-speed gearbox.
* Robert Cordon Champ, 1980, 'The Sunbeam Motorcycle'. Haynes Publishing.