GoogleCustom Search

BSA A10 Golden Flash

BSA A10 Gold FlashBSA A10 Golden FlashBSA 650 Golden Flash

BSA's post-war parallel twina owed an obvious debt to Triumph's trend-setting Speed Twin on the 1930s, but in every detail the design was a true original. In its own way, BSA was as influential as Triumph in making the layout such a staple of the British motorcycle industry in the 1950s and into the 1960s.

There was a further link with Triumph, since some of the earliest design work on what would become BSA's twin was carried out by Val Page, the engineer responsible for the Triumph parallel twin, the 650cc 6/1. More design studies were carried out by Edward Turner, designed of the Speed Twin, during some time spent at BSA in the war years . Most of the detail, however, was the work of BSA chief designer Herbert Perkins, who had been with the company for many years. Near retirement age, he laid down the basis of the 500cc BSA A7, which was launched in 1946.

Among notable differences from the Triumph design were the use of a single camshaft with four lobes, carried behind the engine, instead of separate ones for exhaust and inlet.

Some minor problems with the transmission and other features such as the lubrication were tackled in the ensuing years to make the A7 into a competent and reliable bike, though not one with a particularly high performance.

Much of the work involved in refining the design was carried out by Bert Hopwood. He soon had a further brief when news of Triumph's plans for a larger version of the twin leaked out; BSA decided to follow suit, with a deadline of October 1949, the Earls Court Show. Starting in May 1949, the design work was carried out in around four weeks and the model was in prototype from inside five months. The rush job proved to be worth it as the A10 Golden Flash was a success from the start, with few problems. The Golden Flash name referred to the paint scheme, applied overall, although black and chrome was offered as an option. The new ironbarralled engine gave a useful 35bhp and the then new plunger suspension system added to rider confort, although at the expense of handling as the plunger wore.

Improvements and enhancements were made on both the A7 and A10, including sports versions with high-performance carburettors and tuned engines. The first major change came in 1954, with a new frame and swinging arm rear suspension. This necessitated a change to the transmission. Alloy brake drums followed early in 1956, with a corresponding improvement in stopping power which was needed even more by the sports-tuned Road Rocket, introduced that year and was good for 110mph.

The Golden Flash itself went on year by year earning a reputation for dependability that endeared it to a generation of riders. As fashions changed, so BSA developed hte unit engined A65 model and the A10 was phased out in 1961, although the more sporting Super Rocket was to continue until 1963. That last year saw the introduction of the definative sporting derivative, the Rocket Gold Star. This used a tuned 650cc sports engine in a Gold Star frame - a hybrid that worked so well that it overshadowed BSA's own replacement for the pre-unit 650cc twins, it was a fitting swan song for a much loved model.

BSA A10 Golden Flash

  • Years in production - 1950-61
  • Engine - twin-cylinder overhead valve four-stroke
  • Bore and Stroke - 70 x 84mm
  • Capacity - 646cc
  • Compression ratio - 6.5:1
  • Power - 35bhp @ 4500rpm
  • Gearbox - four-speed
  • Weight - 395lb (plunger)