Royal Enfield Motorcycles

Today in Motorcycle History

Royal Enfield Motorcycles 1914-1915

The New Two-stroke Enfield.

A New Model for The Enfield Co.: Refinements on the Sidecar Outfit.

THE two-stroke Enfield, which made its first public appearance at the Coventry and Warwickshire Motor Club's hill-climb, has been improved out of all knowledge, and will be bound to make a strong appeal to the ever-growing army of two-stroke enthusiasts in 1915. Practically throughout the year the Enfield Co. has been experimenting with a view to producing a reliable two-stroke lightweight for next year's market, and last week we inspected the outcome of those experiments, and are able to present our readers with a description and illustrations. The new Enfield is of really practical design, and, what is more, of attractive appearance - a combination difficult to obtain.

The Power Unit.

The engine is rated at 2¼ h.p., measuring 64 X 70 mm., giving a capacity of 250 c.c. The cylinder is a fine specimen of the foundry worker's art, the fins measuring l¼ in. deep The inlet and exhaust ports are arranged in front, and in juxtaposition - a practice which seems to be gaining favour. The release valve is arranged horizontally just above the ports, and a pipe conveys the released gases into the exhaust.

The piston is of orthodox design, with a deflector on top, and a ring top and bottom. An outside flywheel is mounted on the right-hand side of the machine, keyed to the mainshaft, and the drive to the Enfield two-speed gear in the countershaft is on the opposite side.

Easily Detachable.

Accessibility has been well studied, tor the gear is contained m an aluminium bracket behind the crank case, and on the top of the housing a platform is arranged for the magneto. Thus, by removing two bolts at the rear and one in front of the engine and disconnecting the rear chain, the whole power unit can be dropped but of the frame without disturbing the timing, carburetter, or the pair of engine chains.

Roller bearings of Enfield design are used for both crank bearings, the connecting rod bearing being plain.

The top tube of the frame slopes downward from the head, giving an extremely low riding position. The lank which is shaped to fit the triangle has the oil compartment at the rear, and a pump is provided, together with a connecting pipe to the petrol compartment, to feed oil into the petrol in suitable proportions. An Amac carburetter is used in conjunction with this "petroil" system.

Spring forks of a design successfully used on Enfield productions for some years past have been adopted, with a single spring in front and round section tubing The portion of the rear mudguard from the rear stays, including the carrier, is arranged to be removable by simply slacking two bolts on the end of the chain stays. This feature, which will be appreciated when tyre troubles come along, has also been standardised on the new 6 h.p. sidecar outfit. Aluminium footplates sprung in front are used, and the Enfield cush drive, as on the 3 h.p. mount, is arranged in the rear hub. The standard handle-bars are all black, and with 2in. tyres the machine is to be sold at thirty-eight guineas.

The 6 h.p. Sidecar.

Though there are no startling alterations on the sidecar outfit, many refinements have been introduced, most of which received a test of the most destructive type in the A.C.U. Six Days Trials last July. First of all, the top tube is dropped at the rear end, and the new dome-shaped mudguards should prove very efficient in wet weather. The front guard is exceptionally wide, and side extensions are formed their whole length.

We have already referred to the detachable carrier and guard, which incidentally can be removed in half a minute. The Enfield Co., it may be remarked, was among the first to form the sidecar attachments integral with the bicycle frame, and to produce a motor bicycle specially for sidecar work and sold as a complete outfit.

To enable the rear wheel to be readily removable, the brake is now arranged to operate inside the groove of the dummy belt rim connected to the left-hand side of the driving wheel, though the pedal is on the right-hand side, the, connections being carried in a lug formed with the frame. We were glad to notice the greatly increased strength of the forks, the side plate links being of large flat section, and the bolts secured by castellated nuts and split pins. Both fork and girder are of round section. A permanent lamp support is obtained by extending the handle-bar stem.

As regards the sidecar, the band brake, which we have mentioned was being tested, has been discarded. Again the mudguarding has been improved by the fitting of an inside shield which extends over half the wheel. Tool spaces are arranged both under the seat and under the front of the body, and a spring luggage carrier is standard. The price remains as before, viz., 80 guineas, with an increase of 2 guineas for the 8 h.p. J.A.P.-engined model, and we have already mentioned that the outfit may be obtained, complete with Lucas lighting set and all fittings ready for the road, at £100 complete.

The Motor Cycle, November 5th, 1914. P508A.


The First Model Makes its Appearance at the Coventry Hill-climb

THE Enfield Cycle Co., Ltd., of Redditch, are yet another of our large manufacturers who have turned their minds to the two-stroke question, and the first of their productions in its experimental form made its debut at the Coventry and Warwickshire M.C. hill-climb on Saturday last. It is a very neat looking mount. It is interesting to note that the Enfield engine is in no way a copy of existing machines, but the designer has struck out boldly on lines of his own. Perhaps the most interesting feature is the slide valve employed to control the port openings. It is actuated from the crankshaft, and it is claimed that the petrol consumption is considerably improved by its use. The magneto is carried behind the cylinder, and at present the engine is mounted in a loop frame, though we are given to understand that in its final form a divided frame will be standard and that the engine will be so constructed as to make a unit with the already well-known Enfield two-speed gear.

Accessibility well Studied.

The bore and stroke are 70 x 72 mm. respectively, but the slide valve gives the engine the appearance of having a longer stroke. Care has been taken to render all detail work accessible, and all ports are arranged slightly on the skew, so that they may easily be inspected without interference from the frame. An Amac carburetter was in use, but the type of magneto has not yet been definitely decided on.

The Motor Cycle, September 3rd, 1914. p299.