The model range was reduced for 1927. Sprinting was made illegal on public roads in Britain and the factory dropped its OHV sprint machines. All versions of the short-stroke 499cc side-valve engine motorcycle were also dropped (Models 3 and 5).
Models 1 and 2
Two versions of the 347cc side-valve model were produced: the Model 1 (touring) and Model 2 (sports).
Models 5 and 6
There were also two versions of the 492cc 'Longstroke' side-valve machine: the Model 5 (touring) and Model 6 (sports). The Model 5 had been introduced in 1923 as the 'Light Solo', a short-stroke engine installed in the sportier Longstroke frame - for those who wanted a sporting short-stroke without the standard Model 3 cycle parts. From 1927 the 'Model 5' name was used for the touring version of the Longstroke-engined side-valve.
Model 7
The Model 7 (596cc) side-valve machine continued to be produced, aimed at side-car work. Introduced in 1920, the 4¼ h.p. 600 was soon re-named the ‘Model 7’ and retained the flat-tank styling well into the 1930s, remaining otherwise largely unchanged until 1940.
Model 9
The 493cc OHV Model 9 was produced with a single-port engine, along with its sporting version, the Model 90, with a two-port engine and separate oil tank. The 347cc OHV machine was available only in its sporting Model 80 version with a two-port engine.
Models 80 and 90
Models 80 and 90 were given a "bullnose" petrol tank. "Bullnose" refers to the shape of the tank on the 27/28 models, which was rounded at the front.
Frame and cycle parts
Front forks were strengthened to cope with higher speeds - and after failures in racing, although no failures were reported from road use. The altered forks have parallel front and rear tubes.
In 1927 wired-on wheel rims replaced beaded tyre rims.
The transverse 'coffee-pot' silencer also disappeared from the side-valves, replaced by a pipe curving across the front down-tube to the near-side of the machine.
The side-valves were differentiated by their cycle parts: the inclusion of a rear chaincase and high-level handlebars for the touring Models 1 and 5, and no rear chaincase and lower sports 'bars for the sporting Models 2 and 6.
Sources: sunbeamsidevalve.com, Bonhams, et al.
