Gonthier Motorcycles

The Four-cylinder Gonthier Motor Cycle.

Belgium's First Post-war Production.

BELGIAN motor cycle manufacturers are making rapid recovery, despite the troublous circumstances which are still extant, and that they are not behindhand in following the trend of modern design is evident from the production of a four-cylinder machine at Liege, the town whose name conjures up gallant memories of the early days of the war, and which, in pre-war days, was the home of another well-known Belgian motor cycle, the F.N. The designer and manufacturer, who has got so quickly to work, is M. Henri Gonthier, well-known in motor circles in Liege.

The Engine.

The Gonthier engine has four air-cooled cylinders, each a separate casting, and each with a bore of 55 mm. and stroke of 75 mm., giving a total capacity of 748 c.c. It has overhead inlet valves, operated through adjustable tappet rods. The ball bearing nickel steel crankshaft is mounted on three bearings, following car practice. The pistons, which are of a patented type, carry two rings at the top, and beneath the lower one is formed a deep groove, from which a series of holes give communication to the interior of the piston. Oil is collected in this groove, and any excess is passed through to the interior and so back to the crank case. This must tend to economy in oil and reduce carbon . deposit without starving the piston and cylinder walls to any particular degree. Lubrication is effected by a neat mechanical pump, designed to maintain a constant level in the crank chamber.

The engine, clutch, and gear box form one unit, being carried in the loop of a duplex frame. The frame is well designed, and of ample strength for sidecar work. The forks are girder construction, with coil springs and parallel action.

The clutch is of the plate type, of large diameter, running in oil. The gear box is constructed to give no fewer than seven speeds, with nine gear wheels, of which only two slide on the shafts. It is said to be just as simple to operate as a three-speed gear, and yet it provides a fairly gradual progression from low to high, and vice versa.

At the same time, it is possible to overstep the intermediary gears and change directly from low to top or otherwise, as desired The designer describes the gear quaintly as a three-speed gear with two intermediary gears between first and second, and two more between second and third. A kick starter is fitted

Transmission from gear box to rear wheel is by a totally enclosed chain. The carburetter, specially designed for this machine, is operated by a single lever and has two jets. The second jet comes into action at high speeds.

The vaporising chamber is said to be particularly effective in atomising heavy fuels. As to the fuel consumption we have no information, but the design bears promise of economical results.

The method of springing, to which this firm is particularly partial, is a parallel motion incorporating large coiled springs; it is embodied in the saddle, front forks, and sidecar springing, and should prove very effective. The question of mudguarding has been well looked after, the guards being very wide and substantially made, the rear guard having formed in it a compartment for tools and forming a carrier.

Both wheels are detachable and interchangeable, and when a sidecar is used a spare wheel may be carried.

As regards the sidecar, M. Gonthier claims to be the first to introduce this attachment into Belgium, and makes a distinct departure from usual practice by employing a pressed steel frame with welded joints. The attachments are particularly strong, and the girder type of stay, also of pressed steel, which stiffens the sidecar axle, is a distinctly good point.

The construction of this sidecar chassis is similar to that of aero engine plates, and since so many of our manufacturers have had experience in this class of work during the war, it is not improbable that it will play an important part in motor cycle construction in the future.

As far as we are able to judge, this machine gives great promise, and, provided that production is not interfered with by the aftermath of war, it should form a sturdy competitor in the four-cylinder market.

The firm, previous to the war, was turning out a very useful 3 1/2 h.p. twin-engined machine, and its production is to be resumed shortly. The cylinders are set at an angle of 50°, and it follows standard practice in other details.

The Motor Cycle February 6th, 1919. p130