SPORTS MACHINES ON TEST.

SPORTS MACHINES ON TEST. A RUN ON A 680 c.c. ZENITH.

By A.A.R.

IAM going to permit myself to indulge in a complete 2eulogy on this machine, for it is impossible to criticize any important point in the performance or structural details of the bike. One can usually indulge in a mild grouse concerning such things as front brakes, tool-bags and the like, but even here I am stumped. I tried to persuade myself that the general finish was not so perfect as it is on other machines, but then I looked up the price, regarded the shapely tank and polished handle-bar lug. No; for the price the finish could not be improved upon. The saddle, perhaps ? Well, a Terry or Lycett would certainly be a refinement; but, then, some people like a hard saddle—I do for one. bike that runs more sweetly than the old belt-driven Zenith with its 31 to z top gear. Fashions alter, and my lady must needs don a chain if she is to be in the vogue ; but to be completely up to date, however, she must adopt a 41to i top ratio, and since the 68o c.c. J.A.P. is a faster " revver " than its forerunner, this does not detract from the maximum speed attainable. The maximum speed, by the way, is in the region of 62 or 63 m.p.h., and there is. no difference in controllability at this pace than there is at 30 if you are steadied by the weight of a passenger on the back. Without the passenger it would certainly be desirable to invest in a shock absorber and a steering damper, and though these are not essentials, they should check

Suddenly I am inspired. Those greasers seem too small ; and I make a mental note to mention them in my report, only to find that in all probability the next hatch will be fitted with grease gun lubrication.

Performance on the Road.

On being introduced to the " 68o" Zenith for the first time one is struck by the fact that the handlebars, tank and saddle are all in the same latitude, and one wonders—in these days of dropped frames and riding positions, such as that of the Cotton—whether this will give as comfortable a position as the lower riding attitude affords. Let me say at once that it does-on the Zenith, at any rate ; in fact it is preferable unless one has very short arms. Before I tell of its behaviour on the road, let me explain to my readers that the 68o c.c. Zenith—or at least its predecessor, the 5-6 h.p.—was my first love amongst twin machines, and I have never ridden a

any tendency to " buck " owing to the long wheelbase of this machine.

While on the subject I must mention that the wheelbase is considerably shorter than that of the Gradua model, and the bugbear of skidding which was ever present with the old machine has been entirely eliminated ; in fact it would be hard to'find a machine which behaves better on greasy tram-lines and similar privileges for which we pay the County Councils.

I could write a lot about the engine, but suffice it to say that one can walk beside the machine when it is proceeding on top gear, and from 5 miles an hour to its maximum speed the acceleration is as smooth as anyone could desire. With a flying-helmet on one cannot hear the engine at all, and this, combined with the absence of vibration, gives one the impression of riding a motor cycle driven by steam. To test the long journey comfort a distance of zoo miles was accomplished on full throttle, and neither

SPORTS MACHINES ON

my passenger, the engine, or I seemed any the worse at the finish. Second gear was not needed for any main road hill, and the machine acquitted itself admirably on test gradients.

Constructional Details.

26 X 3 Avon tyres were fitted, and their size helped materially towards the comfort, especially as they were inflated on the soft4ide.

The well-known three-speed Sturmey Archer gearbox is incorporated, and there is no need for the fourth speed, which is indispensable on a single cylinder machine. The gears were quiet, the clutch was perfectly adjusted and efficient in action ; the gear lever was inclined to be in the way of one's knee until the top speed position was reached, but this can be altered by an adjustment on the end of the gear handle. Gear changing could be accomplished quite easily with the knee, a practice which some people prefer, as it leaves both hands free for the bars and helps one to change quicker.

The magneto is well shielded, and although I took the machine through several hundred yards of road flooded to a depth of nearly a foot, the engine fired perfectly all the time.

A strong and reliable mechanical pump is fitted, with an auxiliary hand-pump in the tank. Although the latter was used freely during the course of my test, I could not prevail upon the engine to smoke.

The Druid forks are of stout design, and the front brake is of the internal expanding type, and, incidentally, the most efficient front brake I have ever tried.

The back brake is of the belt rim type, and efficient to the last degree. In fact it saved the life of an elderly lady who made a determined attempt to perish under our front wheel. A policeman, who witnessed the effort, commented on the fact that if all brakes were as good as mine accidents would be very rare. The Amac carburettor gave very good results, acceleration being very even, with plenty of" pick-up " ;

but, at the same time, fierce acceleration was not possible without the use of the gear-box. The Zenith frame still retains its characteristic points, in spite of the fact that many modifications

were necessary when chain-drive was adopted. The old design of placing the stand just behind the engine has been superseded by the more orthodox method adopted, the stand clip being simple and substantial.

Closing Remarks.

Although some may disagree with me (that is until they have ridden the "68o "), I honestly feel that this model of the Zenith can be accurately described as the ideal mount.

It has sufficient power to pull a sporting sidecar smoothly without feeling that one is being cruel, and 55 m.p.h. should be attainable with a combination. Kept in good tune, and after a little running in, 64 m.p.h. would be the maximum speed of the solo machine, which means 50-55 all day long, should one be so " dispoged," with an absolute lack of vibration and complete absence of noise. At the same time, travelling in traffic is a joy, second gear being employed nearly all the time, as one can work on the clutch on this gear, and it is not unpleasant to use up to any speed which can be reached in London.

The Zenith is built at Hampton Court by Messrs. Zenith Motors, Ltd.

MOTORING SPORTSMEN—continued from p. 336.

has been adapted to the conditions of the track, and to let the car teach the driver, rather than be forced by him into attempts on impossible feats. He explained that the car and its driver should be one unit so to speak, and then, when the necessary understanding between the twain has been gained by consistent practice, one may go out for really fast driving.

Space does not permit the inclusion of many useful and interesting pieces of information we derived during the course of our interview, but Capt. Campbell was very clear in pointing out the wonderful opportunities presented by the Brooklands and other race tracks to the student of automobile design.

As may be expected, Capt. Campbell has his own ideas as to the essential features of a successful racing car, and at an early date we hope to give our readers an intellectual treat in the form of an article from his pen on this very fascinating subject.

The BROOKLANDS GAZETTE.

Contents for April.

MOTORING SPORTSMEN: J. C. P. THOMAS.

SUPERCHARGING IN THEORY AND PRACTICE. By H. Ilagens. SPORTING CARS ON TEST: THE SUPER-SPORTS ALVIS. THE LIVE STORY Or " MEPRISTOPHOLES."

MAKMG A BOOK AT BROOKLANDS. By "Long Tom." SPORTING EVENTS or THE MONTH (Illustrated). MOTOR CYCLE SPEEDMEN.

THE3 H.P. SUNBEAM ON TEST.

THE INTER-'VARSITY HILL CLIMB AT ASTON CLINTON. ROUIJD THE CLUBS.