The matter of the proper mileage to expect from a gallon of moter spirit is a very dificult one. Probably in no other country where motors are being used could be found such a wide variety of answers. There are three vital factors—the machine itself, the condition of the road and last of all the type of rider.
One curious fact develops early in the discussion and that is the paradoxical statement that the larger engines use less fuel. If the roads are either rough or tortuous, requiring very low speed the smaller engines consume less fuel. But if the roads are straight and smooth, a horsepower engine with a heavy load will consume less fud than an engine of only two and one-half horsepower. The explanation lies of course in the gears. The smaller machines are single speed affairs and to get a good rate of speed the engine must be run very fast, whereas when once the heavy machine is under way and shifted into high gear the consumption of fuel is surprisingly small. Then too the strength and staunchness of the big machine enables it to go steadily on over rough places, where the lighter machine must apply its brakes and then speed up again.
As for the machine itself the first matter of importance to secure a good mileage is the oil feed. The most common trouble met with is over-supply and faulty distribution. Whatever the comparative damaging effect on the machine of too much or too little oil, it is a fact that too much oil brings the first trouble and cuts down the mileage to a ruinously low figure. Its first effect is to foul one spark plug throwing all the work on one cylinder, which in turn must have a double supply of gas. And it must be remembered that the cylinder which is not firing still takes in and spits cut as much gas as the other. So at the first suspicion that one plug is missing it should be promptly attend to. It would require some expert calculation to determine the mounting rate of loss, but it is evident to any rider that the loss is far greater than it would at first seem. The intermittent firing makes rougher riding and in uneven places a full throttle will be required to get over.
Hien Mirescs Hien Bumpace.
Let us take for a standard of comparison the big twin-cylinder three-speed machines of a weight of 350 pounds. If the roughness or crookedness of the roads is such as to compel the wse of the low ear constantly, no more than 20 miles per gallon can be expected. On continuous middle gear 40 miles
Text read from the printed page and cleaned; old type leaves the occasional error.