BSA B31
Encyclopedia
The BSA B31 is a motorcycle
that was produced by Birmingham Small Arms Company
.
The BSA B31, introduced in 1945, was the first new model introduced by the company after the Second World War. Based on pre-war designs, it used a single cylinder four stroke engine that displaced 348 cc. Initially, it had a rigid frame and telescopic forks, the first use of such on a BSA. It developed about 17 bhp, adequate for the roads of the day and enough to deliver a top speed of around 70 mph (112.7 km/h). It was immediately popular and was soon joined by a 500 cc version, the BSA B33 and competition equivalents, the BSA B32 and BSA B34; the side-car version, with stiffer suspension and different final demultiplication, was known as BB31.
Plunger rear suspension was offered later, with a swingarm
rear suspension frame available from 1954. The model continued in production until 1959, by which time the traditional Lucas magdyno had been replaced by an alternator
and coil ignition
.
The B series expanded through its life to include the famous BSA Gold Star
s, and the bottom half of all engines has much in common with the M series side valve models. The M33, designed for sidecar
work, combined the strong M series frame and the better-performing B33 500 cc overhead valve engine.
Motorcycle
A motorcycle is a single-track, two-wheeled motor vehicle. Motorcycles vary considerably depending on the task for which they are designed, such as long distance travel, navigating congested urban traffic, cruising, sport and racing, or off-road conditions.Motorcycles are one of the most...
that was produced by Birmingham Small Arms Company
Birmingham Small Arms Company
This article is not about Gamo subsidiary BSA Guns Limited of Armoury Road, Small Heath, Birmingham B11 2PP or BSA Company or its successors....
.
The BSA B31, introduced in 1945, was the first new model introduced by the company after the Second World War. Based on pre-war designs, it used a single cylinder four stroke engine that displaced 348 cc. Initially, it had a rigid frame and telescopic forks, the first use of such on a BSA. It developed about 17 bhp, adequate for the roads of the day and enough to deliver a top speed of around 70 mph (112.7 km/h). It was immediately popular and was soon joined by a 500 cc version, the BSA B33 and competition equivalents, the BSA B32 and BSA B34; the side-car version, with stiffer suspension and different final demultiplication, was known as BB31.
Plunger rear suspension was offered later, with a swingarm
Swingarm
A swingarm, or "swinging arm" is the main component of the rear suspension of most modern motorcycles and ATVs...
rear suspension frame available from 1954. The model continued in production until 1959, by which time the traditional Lucas magdyno had been replaced by an alternator
Alternator
An alternator is an electromechanical device that converts mechanical energy to electrical energy in the form of alternating current.Most alternators use a rotating magnetic field but linear alternators are occasionally used...
and coil ignition
Ignition coil
An ignition coil is an induction coil in an automobile's ignition system which transforms the battery's 12 volts to the thousands of volts needed to create an electric spark in the spark plugs to ignite the fuel...
.
The B series expanded through its life to include the famous BSA Gold Star
BSA Gold Star
The Gold Star is a motorcycle made by BSA from 1938–1963. They were 350 cc and 500 cc single-cylinder four-stroke production motorcycle known for being among the fastest bikes of the 1950s...
s, and the bottom half of all engines has much in common with the M series side valve models. The M33, designed for sidecar
Sidecar
A sidecar is a one-wheeled device attached to the side of a motorcycle, scooter, or bicycle, producing a three-wheeled vehicle.-History:A sidecar appeared in a cartoon by George Moore in the January 7, 1903, issue of the British newspaper Motor Cycling. Three weeks later, a provisional patent was...
work, combined the strong M series frame and the better-performing B33 500 cc overhead valve engine.