1952 B.S.A. A10 Golden Flash
Bringing back to life a 1952 B.S.A. Golden Flash
It’s easy to see where some motorcycles get their name.
Take, for instance, the B.S.A. A10 Golden Flash. Introduced late in 1949 as a 1950 model, B.S.A.’s Golden Flash was the first 650cc parallel twin in the company’s range. And, it was finished in a sandy beige – almost gold – colour. This was at a time when most other British motorcycles came in dour black on black.
The A10 was a logical progression from the B.S.A. A7, a post-war 500cc parallel twin motorcycle that was designed by Val Page and Herbert Perkins. Launched in 1946, the A7 was by all accounts a solid and staid mount, but was saddled with lacklustre performance.
When news broke in 1949 that B.S.A.’s competition, Triumph, was developing a 650cc twin the Birmingham Small Arms company had to respond. B.S.A. designer Bert Hopwood was given the task. He engineered the 646cc A10 powerplant with overhead valves and single camshaft – this placed behind the cylinders. The A10 had to be ready in a few short months, and to shave development time the 35 horsepower 646cc engine simply bolted straight into the A7 chassis. The frame, fork and wheels of the 500cc machine were more than strong enough to handle the extra power output of the new and larger 650cc engine.
By 1950 both the A7 and A10 featured plunger rear suspension. Prior to plunger suspension, the B.S.A.’s had a rigid rear frame. Simply stated, plunger suspension sees the axle of the rear wheel mounted between an upper and lower spring in a pair of towers either side of the rear frame, thus effecting a form of suspension. However, plunger-style rear suspension did not last long. In 1954 a more modern full swingarm setup with dual shocks was introduced to both the A7 and A10 range. The A10 carried on with the Golden Flash, and other variants such as the Super Flash, until 1963.
When it comes to finding and restoring a motorcycle there are easy ways and hard ways. The easy way is to restore a complete machine. The harder way is to take on a basket case project, one where the previous owner has dismantled the bike. And one of the hardest ways is to pick up bits and pieces, eventually building a complete motorcycle from parts.
And that’s how in 2003 B.S.A. fan Grant Sauerberg of Calgary acquired this project. He rescued a derelict and slowly rusting B.S.A. A7 chassis – exactly the same as an A10 frame — from under the back porch of a house. Lacking an axle the front wheel was loosely held in the forks with an oversized Philips screwdriver shaft. In the garage of the same house were several pieces of A7 and A10 motorcycles, but the only semi-complete engine was a 1952 model year 650cc A10 powerplant. Included in the package was one brand new B.S.A. Golden Flash gas tank that had never seen the light of day and a new old stock dual saddle.
While those brand new pieces made the package rather attractive, Sauerberg still had his work cut out for him. Several key parts were missing including the correct front fender, oil tank, headlight and instruments, controls, chainguard and air box. The engine was minus the cylinder head, carburetor, clutch and primary covers.
But for Sauerberg, it is the hunt for elusive and critical components that he enjoys. “I’d rather build a bike up from parts than do a complete motorcycle – there’s a lot more pride when you’re all done. I enjoy starting with the worst, and making a silk purse out of a sow’s ear; I do like the serious challenge.”
With his B.S.A. project home in his garage Sauerberg got to work stripping the sub-assemblies down and taking stock of the parts he did have. A list of missing pieces was drawn up, and Sauerberg contacted many of the British parts suppliers in Canada, including British Cycle Supply, Motoparts, Moto Montreal and Walridge. He found some used parts such as the correct front fender locally, and a fellow B.S.A. enthusiast in Crowsnest Pass supplied the correct headlight, engine pushrods and springs for the rear plungers. What he could not find, he made, and that included the air filter/battery box.
What was left of the engine came apart, and the cases were cleaned up with soda blasting – a less aggressive form of grit than glass or sand. The engine was rebuilt with all new bearings, and the crank was turned and fitted with undersized shells. The cylinders were bored and new pistons and rings fitted, and the head – which he located at a Red Deer swap meet – was treated to new guides and valves. Ignition is by Lucas K2F magneto, and he took what he had on hand apart and installed new bearings and spark shields. When he was done, the mag threw a good, strong spark.
“I wasn’t building a race engine, but I wanted a good, sound motor,” Sauerberg says of the rebuild. The gearbox was opened up, but was found to be in decent nick, so was not completely disassembled.
Sauerberg ordered new rims and spokes for the wheels. The rim centres were painted gold to match the colour of the bike, and the hubs cleaned, painted, and fitted with new bearings. He laced and trued up the wheels, and had the rims hand striped in red paint to separate the gold centre from the chrome rim. As luck would have it, Sauerberg had a complete set of front forks that he had rebuilt for another project, but he had gone in a different direction with that particular B.S.A. So, the hydraulic forks were surplus to requirements, and they were put into service in the Golden Flash.
The frame required little attention save for some work to the springs in the rear plungers. Paint was computer matched to the colour of the new old stock gas tank, and Sauerberg painted most of the machine himself. He did, however, have the front and rear fenders and the toolbox professionally sprayed. Assembly of the B.S.A. was smooth and straightforward, and the project was topped off with a brand new AMAL pre-Monobloc carburetor. According to Sauerberg, this instrument was the single most expensive component he bought for the motorcycle.
“This was a very lovely bike to work on,” Sauerberg says of the Golden Flash. “It didn’t seem to fight me as much as other projects I’ve done.” And, hot or cold, the B.S.A. is a one-kick starter. When he had only 35 miles on the clock Sauerberg took the machine on a 450 mile Geezers on Wheezers tour in northern Alberta. Nothing broke, and the machine required very little fettling. Now, the B.S.A. has logged some 2,200 essentially trouble-free miles.