Four-stroke Singles in Three Popular Sizes. Sporting Model based on T.T. Type.
PRESSED steel construction has been a feature of the Beardmore-Precision machines since 1919, and it is even further developed for 1923, even the back stays being of steel pressings in the latest models.
Of course, the welded steel tank which forms the main frame member is retained. On this tank now are welded lugs for the suspension of the front end of the saddle, while part of the mudguards form integral members of the frame.
An addition to the Beardmore range is a side-by-side valve outside flywheel machine, having a bore and stroke of 70x90 mm. (346 c.c.). This little engine is sturdily built throughout, having a carefully designed one-piece cylinder; ample cooling area is provided, and the cylinder held down by a base flange.
Floating in a cast-iron piston suitably finished with bronze bearings is a very large diameter hollow gudgeon pin, and the fixing employed for this part is one the most ingenious features we have encountered. End pieces which pass to the gudgeon pin and lock in suitable recesses in the piston bushes are formed in phosphor bronze and have an internal thread; screwing into these threads is a tightly coiled tension spring. In order to erect the gudgeon pin and the piston, one end piece is screwed tightly on to the spring and the other end piece screwed down as far as possible; the next step is to pass a wire spoke through the first end piece until it presses against the further piece, thus stretching the spring, the further end piece is then fully screwed home and the spring released so that the locking device takes up its position in the slot and firmly holds the gudgeon pin in place.
The H.-section connecting rod has a double row roller bearing, the crank-shaft being of the built up type carried in a double row ball bearing on the flywheel side and a single row on the timing side. Both valves are operated by a single cam through a rocker gear. On the outside a cap nut is fitted, which also operates as a flywheel drawer.
The primary chain runs at the outside of the fly-heel and it is enclosed in an aluminium pressing, while the, rear chain is protected by a light steel guard, a three-speed Sturmey-Archer box with shock absorber in the clutch being employed. The bracket for the gear-operating level is brazed to the frame, thus doing away with unsightly and heavy clip joints.
Behind the engine lies a magneto mounted on a separate aluminium bracket so as to be easily adjustable.
A modification of the Beardmore Tourist Trophy fork having a horizontal leaf spring and vertical pressed steel member is fitted. This fork, of course, is pivoted at the crown.
A large diameter band brake is fitted to the front wheel, and an internal V brake is employed with a dummy belt rim on the rear wheel. 26in. 2¼ in. tyres are. standardised, the rim and mudguards permitting the use of 2½in tyres for side-car work, if so desired.
A simple petrol filter is part of the design, and the wheelbase is only 50in.
With the standard compression ratio of 4.25 to 1, the little Beardmore-Precision is a fast and handy mount.
A modification of the T.T. engine has enabled the firm to list a sturdy machine in the 500 c.c. class which is suitable for both solo and sidecar purposes. This engine follows the lines of the well-known 598 c.c. Precision, being formed as a unit with the three-speed gear box. A method of adjusting the front chain has, however, been added. The bore and stroke are 81.1x96 (498 c.c.), and the engine may be obtained with compression ratios of 4½, 5, or 5.7 to 1, according to the uses to which it is to be put.
Detail modifications include a modified cylinder head, a finned exhaust valve cap, a short ribbed aluminium exhaust branch, and a folding kick-starter.
A considerable alteration has taken place in the forks, which are now of the link type instead of being pivoted, though the usual Beardmore type of leaf spring is employed.
The remarkably sensible type of combined tool case and carrier which is a feature of the makers' machines is incorporated at the rear, and the whole of this unit, together with the mudguard, can be detached in the neighbourhood of the back stays to facilitate tyre repairs.
No decompressor it fitted to the 498 c.c. engine, but flexible feed tubes and a very easily detachable filter are refinements of some importance. Two gallons of petrol may be carried in the pressed steel tank and the saddle peak is attached to the top of this unit. Tyre size is 700x80 mm.
The 598 c.c. big single machine remains largely unaltered, but, as is the case with other Beardmore-Precision models, it is fitted with front hubs of the makers' own manufacture, carrying 3/8 in. balls.
The list price of the 346 c.c. machine is £75. £80 is the figure for the 498 c.c. model (£100 with sidecar), while the 598 c.c. sidecar outfit is £110, or £85 in solo form,
The Motor Cycle November 9th, 1922. Page 663