1959 | BSA B 31

BSA’s rugged, workaday B31 was manufactured from 1945 to the end of 1959, its overhead-valve engine providing the basis for the renowned Gold Star sports roadster.
At the time of its introduction, the B31 was BSA’s sole all-new model, joining the lightweight ‘C’ and heavyweight ‘M’ ranges carried over from pre-war days.
Produced initially with rigid frame and telescopic front fork, the B31 gained (optional) plunger rear suspension in 1949 and an all-new swinging-arm frame in ’54.
A good all-round performer by the standards of its time, the B31 could cruise comfortably all day at 60mph while returning 75-plus miles per gallon, virtues that endeared it to private owners and police forces alike.
“The Motor Cycle” published a 1000-mile road test of the B31 in its August 23, 1956 issue and commented favourably on its steering and roadholding qualities, and concluded that the B31 was ”an attractive model for the rider who wants a lively, economical, easy-to-handle all-rounder but who is not insistent on a ultra-high maximum speed.”
The former owner decided to tackle that last point: the bore was enlarged to create a cubic capacity of 440cc, a Triumph 750 piston and Mikuni carb were fitted and the original B31 cams were exchanged for “Gold Star” touring cams.
The Inlet valve is a B33 type and the Lucas ignition has been exchanged for a Beck electronic unit.
Both Smiths speedo and rev counter are electronic too.
Looks and weight are improved by the fitting of aluminium mudguards; the alu rims are Akront items.
This Goldstarized B31 is in fine condition throughout and ready for the road.