Classic Bikes Custom Bikes Individual Racing Bikes AJP AJS Aprilia Ariel Avinton / Wakan Bajaj Benelli Beta Bimota BMW Brough Superior BRP Cam-Am BSA Buell / EBR Bultaco Cagiva Campagna CCM CF Moto Combat Motors Derbi Deus Ducati Excelsior GASGAS Ghezzi Brian Gilera GIMA Harley Davidson Hero Highland Honda Horex Husaberg Husqvarna Hyosung Indian Jawa Kawasaki KTM KYMCO Laverda Lazareth Magni Maico Mash Matchless Mondial Moto Guzzi Moto Morini MV Agusta MZ / MuZ NCR Norton NSU Paton Peugeot Piaggio Revival Cycles Roland Sands Royal Enfield Sachs Sherco Sunbeam Suzuki SWM SYM Triumph TVS Ural Velocette Vespa Victory Vincent VOR Voxan Vyrus Walt Siegl Walz Wrenchmonkees Wunderlich XTR / Radical Yamaha Zero Video Technical
Complete Manufacturer List

BSA B40

Make Model	BSA B40 / WD40
Year	1936
Engine	Four stroke, single cylinder, Overhead valve
Capacity	343 cc / 20.9 cub in
Bore and Stroke	79 x 70 mm
Compression Ratio	7.0:1
Oil capacity	2.8 L / 5.9 US pints
Cooling	Air cooled
Lubrication	Dry sump
Carburetor	Amal 396, 397 or 398
Exhaust	Single
Ignition	Magneto
Battery	12V, 8Ah
Spark Plug	N4
Starting	Kick starter
Clutch	Multi-plate with cork insert
Max Power	14.7 kW / 20 hp @ 7000 rpm
Transmission	4-Speed, foot gearshift
Final Drive	Chain
Gear Ratios	1st 12.3 / 2nd 9.6 / 3rd 6.9 / 4th 5.8:1
Frame	Full cradle of welded tubular construction
Dimensions	Length: 2100mm / 82.6 in. Width: 750 mm / 29.5 in. Height: 1080 mm / 42.5 in.
Wheel Base	1360 mm / 53.5 in.
Ground Clearance	159 mm / 6.3 in.
Seat Height	813 mm / 32 in.
Steering head angle	65°
Turning Circle	4.4 m / 14.5 ft
Front Suspension	telescopic, coil spring, hydraulically damped
Rear Suspension	Swinging fork, coil spring, hydraulically damped units
Front Wheel Travel	127 mm / 5 in.
Rear Wheel Travel	70 mm / 2.75 in.
Front Tyre	3.00 x 18, Trials universal
Rear Tyre	3.50 x 18, Trials universal
Front Brake	1.125 x 7 in., mechanical
Rear Brake	1.125 x 7 in., mechanical
Wet Weight	165 kg / 364 lbs
Fuel Capacity	15.9 L / 4.2 US gal
Average Speed	Surfaced road: 88 km/h / 55 mph Cross country: 40 km/h / 25 mph
Average Range (@ 64 km/h / 40 mph)	322 km / 200 miles
Average Consumption (@ 64 km/h / 40 mph)	4.5 L/100 km / 22.2 km/l / 52.2 US mpg

These machines were the early post war replacements for the remaining fleet of BSA M20's and Matchless GL3's which, together with the US built machines, had formed the major component of the Army's wartime motorcycle holdings.

The B40 with telescopic front forks was a modern motorcycle in its day and was used for convoy control, messenger services and the carriage of any small stores, which could be fitted into the pannier bags. The carriage of messages was an important function at a time when radios were few, and less reliable than now. Shepherding road convoys, particularly on major exercises, with the British Army of the Rhine in Germany, was a vital function. Motorcycles ensured that units did not become muddled, as there was often a set time allocation for the use of roads by military traffic with no allowances for losing the way.

The B40 like most military motorcycles of the period was basically a road machine with limited off road performance.

It is suggested that the total number supplied to the British Armed forces was 3,087, which included 141 for the RAF and 34 for the Royal Navy. BSA received a further order for an additional 235 machines in 1971, which the company was unable to fulfil due to its increasingly precarious state at the time.

As well as serving in the British Army, Royal Navy and Royal Air Force, the WD B40 was sold to the armies of Australia, Denmark, Jordan to name a few.