A BIG TWIN SOLO MOUNT

The 980 c.c. Brough-Superior Designed for the Sporting Rider.

FOR some time past we have been urging that the claims of the purely solo rider should receive special attention. The 1920 Olympia Show demonstrated the fact that many manufacturers once again have their eyes on this important market. Unfortunately, however, one of the most interesting products of specialisation in this direction was completed just too late for the exhibition.

Mr. George Brough, whose performances in many trials, notably the Scottish Six Days, are well known to most motor cyclists, decided, some mouths ago, to specialise on a super sporting machine, and informed us at that time that it was his intention to produce a fast, light, and well-equipped motor cycle, which should include all necessary fittings, but no fancy attachments, and, after inspecting his latest production, we may safely say that we have never examined a more sensibly equipped big twin solo mount.

To begin with, large tyres (700x80 mm.) are used, and the designer has not forgotten that mudguarding is just as important for the solo rider as for the sidecarist. In consequence, really wide guards, with deep valances, are included. The chains, it is true, are covered only as regards the top run, but the majority of sporting solo riders will prefer this accessible arrangement to the entirely enclosed type.

The popular 90 x 77 mm. overhead valve J. A. P. engine has been specially redesigned to suit the requirements of Mr. Brough, and the light rocker gear and superb finish are outstanding features which catch the eye. Added to this, we are told that, with the aid of a special Amac carburetter which is being supplied for the machine, the engine will tick over at the merest "crawl" and yet accelerate with a rush.

In proof of this statement, each machine will be guaranteed to do from 8 to 80 m.p.h. on top gear. It is never an easy matter to dispose of the exhaust pipes of an overhead valve engine, but, in this case, the difficulty has been overcome in an extremely neat manner.

A well ribbed cast iron port is screwed on to each exhaust outlet, taking the place of the usual exhaust pipe nut and the curves necessary to avoid the frame tubes are smooth and easy. From these ports, pipes lead to a large two-piece aluminium silencer placed forward of the engine and below the magneto; from this silencer a tail pipe extends rearwards.

High Gear Ratios.

To the bottom bracket is attached a Sturmey-Archer gear box, having strengthened teeth and a six-plate clutch. The gear ratios provided by this box are 2.94-1, 4-1, and 5.9-1; such high ratios are, of course, only suitable for high-powered solo machines, but with the excellent pulling qualities of the overhead valve J. A. P. engine they should be low enough for any ordinary work, and, incidentally, .should provide extremely nice top gear running at medium and high speeds. An Enfield type shock absorber is mounted in the rear wheel, in order to mitigate any tendency to "snatch."

Compactness characterises the framework, and, by means of careful design, it has been found to be possible to house the big engine in a machine having a wheelbase of only 55in., and a saddle height of under 30in. Naturally, a sloping top tube is used, and the large saddle tank is rounded giving a capacity for no less than 2½ gallons of petrol and half a gallon of oil.

Two points immediately strike the observer's eye; first, that the large filler caps are of the hexagonal composition type frequently used on car radiators, and, secondly, the plated finish which is set off on the upper surface by a black panel with a narrow gold line to relieve the meeting of the two colours. It is, perhaps, surprising that sidecar lugs should be incorporated in the frame of a purely solo motor cycle, but it is a proof of the fact that Mr. George Brough knows his public, for sooner or later someone will attach a sporting sidecar, and integral lugs are certainly preferable to clip joints.

Ready for the Road.

All detail work is beautifully carried out, and there is an absence of clips which will gladden the eye of the critic. The handle-bar is brazed into the head ball race lug, and a special lamp bracket springs from the base of the Brampton Biflex forks; incidentally, an acetylene lamp and generator will be supplied as part of the equipment unless Lucas mag-dyno is specially ordered.

The Motor Cycle December 23rd, 1920. Page 854