The BSA Thunderbolt was a
British
British may refer to:
Peoples, culture, and language
* British people, nationals or natives of the United Kingdom, British Overseas Territories and Crown Dependencies.
* British national identity, the characteristics of British people and culture ...
motorcycle
A motorcycle (motorbike, bike; uni (if one-wheeled); trike (if three-wheeled); quad (if four-wheeled)) is a lightweight private 1-to-2 passenger personal motor vehicle Steering, steered by a Motorcycle handlebar, handlebar from a saddle-style ...
made by
BSA at their factory in Armoury Road in
Small Heath,
Birmingham
Birmingham ( ) is a City status in the United Kingdom, city and metropolitan borough in the metropolitan county of West Midlands (county), West Midlands, within the wider West Midlands (region), West Midlands region, in England. It is the Lis ...
between 1962 and 1972. Fitted with a single carburettor it was capable of over .
Development
The BSA Thunderbolt was designed as a touring motorcycle. A traditional air cooled 650 cc twin cylinder with a single large bore
Amal Monobloc carburettor, it did not suffer from the same level of vibration as earlier BSA twins and could comfortably cruise at . and reached over . in road tests.
The BSA development team decided to keep costs down by re-using the well proven single sided front brake from the
BSA Gold Star and the same full race camshaft as the
BSA Lightning. Fitted with 12 volt electrics, a
Zener diode
A Zener diode is a type of diode designed to exploit the Zener effect to affect electric current to flow against the normal direction from anode to cathode, when the voltage across its terminals exceeds a certain characteristic threshold, the ''Z ...
voltage regulator and twin coil ignition, the Thunderbolt sold well in the important US import market and with the fuel tank gave a range of .
From 1968 the Thunderbolt benefited from a number of minor improvements including a longer kick start to make starting easier and metal tank badges to replace the earlier plastic ones, which had a tendency to crack. An
Amal Concentric carburettor dealt with the problems of fuel flooding experienced with the earlier monobloc carburettor, by having the float bowl arranged centrally around (concentric with, hence the name) the main jet to remove the sensitivity to fuel surge inherent in all the earlier designs. Stiffer suspension improved cornering but poor quality control and production problems on the BSA assembly line with later models led to oil leaks and rusting parts which damaged the reputation of the Thunderbolt, which was already struggling to compete against the emerging Japanese motorcycles of the early 1970s (such as the
Honda CB750
The Honda CB750 is an air-cooled, Transverse engine, transverse, Straight-four engine, in-line-four-cylinder-engine motorcycle made by Honda over several generations for year models 1969–2008 with an upright, or Types of motorcycles#Standard, ...
) and production ended in 1972.
T65 Thunderbolt
In order to fulfil existing export orders after production of the BSA twins had stopped, between 200 and 300
Triumph TR6 Trophys were rebadged as BSA T65 Thunderbolt and exported to Spain and Australia.
See also
*
Birmingham Small Arms Company
The Birmingham Small Arms Company Limited (BSA) was a major British industrial combine, a group of businesses manufacturing military and sporting firearms; bicycles; motorcycles; cars; buses and bodies; steel; iron castings; hand tool, hand, po ...
References
{{BSA motorcycles, state=collapsed
Thunderbolt
A thunderbolt or lightning bolt is a symbolic representation of lightning when accompanied by a loud thunderclap. In Indo-European mythology, the thunderbolt was identified with the 'Sky Father'; this association is also found in later Hel ...
Motorcycles introduced in 1964