CarBrandLogos archive · BSA · 1965

BSALightning

The twin-carburettor sports version of BSA's unit twin, quick and fragile in equal measure.

Photo: Stavros1 · CC BY-SA 3.0

The story

A defining chapter in BSA history.

Explore the ideas, engineering and context that shaped the BSA Lightning, then continue into its specifications and place in the marque's lineage.

Origins

The A65 replaced the old A10 with unit construction, putting engine and gearbox in one casting for a lighter, tidier machine. The Lightning, introduced in 1965, was the sporting version: a 654 cc overhead-valve parallel twin with twin carburettors, a four-speed gearbox and chain final drive, built at Small Heath and aimed largely at the American market where BSA sold most of its big bikes.

BSA Lightning · Thruxton · CC BY 3.0

Design and engineering

It was fast enough to matter, and good-looking in the way British twins were at the point they had run out of development money. The problems were the ones that eventually sank the industry: crankshaft and bearing durability under sustained hard use, vibration, and oil leaks that customers had stopped tolerating once Japanese alternatives existed. Later machines gained improvements including a stronger bottom end and, on final versions, an oil-in-frame chassis that raised the seat height and was widely disliked.

In production

Production ran to 1972, by which time the Rocket 3 triple and Honda's CB750 had made a pushrod twin look like the past. The Lightning is remembered fondly by owners who have sorted one out, and warily by everyone else.

At a glance