From the archives. Inner workings.

A look at the rockers and valves reveals the eminently rational layout and design of the BSA unit construction motor:

The entire valvetrain is easily accessible by removing a single cover retained by six nuts (below); this is a far more modern idea than what we find on contemporary Triumphs or Nortons.
There is a deep enough "lip" on the edge of the cylinder head to avoid oil leaks here, something that seems to work at least on mine.

Moving onto the starboard side of the motor, we see the timing gears, oil pump below them (exploded, in the following photo), and the gearbox at the rear. All a very compact, efficient and rational layout:

The gearbox itself can be pulled out as a complete mechanism (save for top gear, which stays in the crankcase):

While the A50/A65 is not a true unit construction motor in terms of lubrication (oil is still separate for engine, gearbox, and primary transmission) this is an evolutionary leap for the year 1962 and the result is a compact powerplant that packs "zesty performance" - as the press of the time would say - into a small and relatively lightweight vehicle.

Here are some cam lobes:

At the very front, and at the very rear of the bike we find wheels. Together with the front forks, these are matching Triumph/BSA oil-in-the-frame (OIF) components, which I didn't necessarily choose from the outset, but it just happened this way in my gradual search for parts.

It all started from a pair of OIF rims, which were donated by a good friend:

The spoke drill pattern means you have to use conical hubs, so at that point everything else followed, and I'm glad it did as it makes for a much more coherent set-up. There's nothing wrong with mixing parts from different makes and years when building one of these contraptions, but it's a different style (and you'd better remember where everything comes from, when you need to order spare parts!).

A rear conical hub was procured, after a very long search to source what ended up being the most elusive part of the entire project:

A matching brake plate and all-new components for the brake:

The front brake has a very sporty looking air scoop, a bit odd on a chopper, but I like it: