Details of the 1915 Harley-Davidsons

Told in Non-Technical Language

By Unknown, Photography by Unknown

In Brief

A new twin, of same piston displacement as for 1914, but 11 h.p. and 65 m.p.h. guaranteed, with three-speed sliding gear transmission, integral with free-wheel device and step-starter, on countershaft.

A guarantee of 6 h.p. and 50 m.p.h. for the single, of same displacement as in 1914; this single being with or without rear-hub two-speed gear.

A stripped stock model, for racing, with 11 h.p. guaranteed and “no end of speed” already demonstrated.

A new automatic-mechanical oil pump, constructed to feed right under all conditions; larger motor parts; larger sprockets; wider chains; lower saddle position; quick detachable, much more durable muffler; and so on.

Five models in all-the 11 h.p. 3-speed, $275; 11 h.p. 1-speed, $240; 6 h.p. 2-speed, $230; 6 h.p. 1-speed, $200; 11 h.p. stripped stock, $250. All prices F.O.B. factory.


LADIES AND GENTLEMEN: Permit us to introduce to you the 1915 Harley-Davidson models; five of them-a single, guaranteed to develop 6 h. p. and 50 miles per hour; the same, with the rear-hub two-speed gear; a twin guaranteed to develop 11 h. p. and 65 miles per hour; the same, with a new three-speed gear, integral with the free-wheel device on the countershaft, instead of on the rear wheel; and a 11 h.p. stripped stock model for those who especially want “some” speed, at short or long distances; all of these, with a new automatic mechanical oiler and a right smart lot of other practical improvements, at even lower prices than were charged for 1914 models which had fewer improvements.

Something has been said, on the Coast, about electric equipment. Maybe this is a feature to be divulged at the Chicago show. Maybe it is just a rumor. If it is to be, no doubt it will be at an extra charge.

Look at the illustrations in this issue. Though there are 29 changes and refinements in the 1915 twin motor, the general lines of the Silent Gray Fellow remain the same single or twin. The saddle position is two inches lower, and firmer. The position usually occupied by the clutch lever is now used for the three-speed lever. The two-speed gear on the single remains in the rear hub. In the twin the three-speed gear, step-starter and free-wheel device are all on the countershaft.

The increased horse power does not mean increased piston displacement. This remains the same as it was in the 1914 models, the 8 h.p. and 5 h.p. respectively. The makers claim to be the first to guarantee a given speed and horse power. They are the first makers in the United States to announce motorcycles with three-speed gears. They say that more than 50 per cent of the machines produced for the 1914 market were fitted with two-speeds-more than of all other models combined; and that 75 per cent of their 1915 output will be three-speed.

The Two New Models

Detailed specifications of all the models will be found in the special Harley-Davidson announcement in this issue. A few words about the two new models, 11-F and 11-K, the three-speed for road use and the stripped stock model for short and long distance speed work, respectively.

The New Three Speed

Model 11-F, the new three-speed machine, is described as the logical machine for touring, side car and all-around general usefulness. “As the two-speed twin greatly increased the touring radius of motorcycles and side cars, so will the Harley-Davidson three-speed twin increase the radius over the 1914 standard.”

The Stripped-Stock Terror

Model 11-K, the 11-h.p. stripped stock twin, for speed work, had already established its success before it was placed in the 1915 line. The first appearance of this model was at Dodge City, Kas., July 4, where, in the 300-mile international race, Walter Cunningham covered 120 miles in 105 minutes flat, averaging 68.18 miles per hour. At Rockford, Ill., August 9, Alvin Stratton rode one of these models in the 100-mile race, covering the distance in 97 minutes 2 seconds, averaging 61.8 miles per hour. In the 250-mile event at Sioux City, Ia., September 2, William Brier covered the distance in 3:47:30, averaging 65.93 miles per hour and doing 74 miles in the first hour. At Little Falls, N. Y., July 29, Herman Lewis rode one of these models around a 4 ½ -course in 3:30, averaging 74.69 miles per hour. For prolonged, excessive speed, Model 11-K stands A-1.

New Motor Construction

The carburetor has been said to be the heart of a motor, but the motor is “the main works,” and for several months the runaways performed by a new Harley-Davidson motor, of which the recently announced and marketed improvements (shorter push rods, quicker-opening valves) have been but hints, have been setting the motorcycle public by the ears.

A Bold Guarantee

Now comes the bold announcement that, for the road twins, 11-C (two-speed) and 11-F (three-speed) twins, 11 horse power and 65 miles per hour are absolutely guaranteed; and for the road singles, 11-B (single-speed) and 11-C (two-speed), 6 horse power and 50 miles per hour. The speed of the stripped stock twin has already been plentifully demonstrated.

The company state that the improvements in their motors for 1915 are greater than any they have ever made, and that power curves, which will be illustrated in the catalog, show for the twin a developed horse power of 16.7 at 3400 revolutions, and for the single 7.6 at 3200 revolutions. Both motors, it is stated, are actually developing far in excess of these figures-close to 22 horse power, in fact, for the twin

A New Motor Throughout

The illustration in this issue helps some, but actual comparison with former models will show, even outwardly, the larger dimensions of the manifold, intake passages, oil pump, etc. The increased power and speed, however, are largely due to interior changes. Increasing the diameter of the crank pin and widening the bearing surface has worked wonders. The inlet valve has a 45-degree seat instead of being flat, and has larger diameter. The gasoline feed pipes are larger. Incidentally, the carburetor can be removed without disturbing the manifold; and there are other interesting details. The 1915 Harley-Davidson motor is claimed to be a new motor throughout. For this the changes mentioned are partly responsible, but other important changes are new cylinders, the faster valve mechanism and heavier fly wheels. There is precise lubrication at any speed or crank case pressure; perfect gas combustion; perfect scavenging; elimination of motor vibration. This means increased power, speed, life.

Some Important Changes

The new twin crank pin bearing is a four row Harley-Davidson roller bearing, a set of two rows of rollers running on each connecting rod, both on the same crank pin. This bearing is claimed to require the least lubrication of any known type, and is absolutely noiseless and as near frictionless and wear-proof as possible. The contact being rolling, not sliding, is non-heating. This bearing was evolved and is entirely produced in the Harley-Davidson plants.

The crank pin, formerly 7/8- inch is now l-inch, and the bearing is 1 ¾ instead of 1 3/8- inch- an increase of 46%.

The rotary breathing valve, gear-driven, which has proved so successful, is a feature, of course. It eliminates the hissing noise in twins. It reduces the crank case pressure on the down strokes of the pistons 70%, increasing the motor speed more than 50 revolutions per minute and preventing road dust entering the motor through the breather pipe.

Twenty-nine in All

All told, there are 29 changes and improvements in the 1915 twin motor, and corresponding refinements have been made in the single motor where they have been found advantageous.

In the single, due partly to the larger intake pipe, larger carburetor, larger inlet ports, larger inlet valves with the new 45% seats, with the same piston displacement as formerly, exhaustive tests show an average saving of close to 30% in gasoline consumption over the former 5 h.p. motor.

Same Displacement, Greater Power

The piston displacement remains unchanged (60.34 for the twin, about 35 for the single), but the power output for the twin is greater by 31% at 2500 revolutions per minute and 47% greater at 3000 revolutions. The improvement in the output of the single has also been great. At the same time, there is marked decrease in gasoline and oil consumption and higher all-around efficiency. The new twin motor is claimed to show absolutely no vibration on the road. As to its flexibility and accelerative powers, a claim of 65 m. p. m. from a standing start, in 330 feet, is made.

The Three-Speed

The three-speed gear for the 1915 Harley-Davidson is a ‘’regular automobile fellow.” Outwardly not conspicuous, its “bones” are large and husky. It’s the big Harley-Davidson feature for 1915. The illustrations in this issue show that in the three-speed model the free-wheel feature, which with the two-speed is at the rear hub, is now at the countershaft, integral with the three-speed gear. The change only slightly alters the line design, which remains distinctly that of the Silent Gray Fellow.

Eight Thousand Miles Without Wear

The gears are claimed to be noiseless and can be banged back and forth without injury. They are eight pitch and have a half-inch face-as big as gears used in many automobiles. The distance between centers is short. The spline shaft and jack shaft are so close together that there is no play. The rigidity of the gear box is such that some of the machines in the engineering department have been run 8000 miles without any indication of wear or play in any part of the gear.

A Case of Three-in-One

The step-starter, the clutch and the three-speed are mounted together on a drop forging which is part of the frame. The front chain can be adjusted by simply sliding this unit on the frame. It can be locked instantly and the adjustment is such that the transmission is always in line. The rear chain is adjusted in the usual way.

An illustration of the top of the gear box shows the locking mechanism, by which it is made impossible for the gears to be shifted without releasing the clutch, thus doing away with any chance of stripping gears through carelessness.

Value of the Intermediate

For side car purposes the three-speed is ideal. With the standard gear of 3.89, used on the twins, the intermediate gear of 1 ½ gives a ratio of 5.83. In traffic or rough going, the motor can be run on the intermediate indefinitely- a relief from racing the motor on the low. The low gear, with its Increase of 2 ¼ gives ratio of 8.75, which ought to pull both the driver and his side car passenger through almost anything.

To accommodate this increased power, the chains and sprockets are larger. Both are 1/8-inch wider and the three-speed model has a 16-tooth engine sprocket. This it is believed, will more than double the life of the transmission.

It is claimed that, in the low, the new model will climb a 45% grade with side car and passenger, and that it has taken a 60% grade without side car, “without a murmur.” The touring radius of the three-speed twin is claimed to be double that of a two-speed machine. As for care, -no adjustments; a little oil now and than, that’s all.

Changes in the Two-Speed

The two-speed gear used for the single, Model 11-C, is essentially the same as in 1914, but a Harley-Davidson roller bearing is now used for the main hub bearing on the left side, and a ball-thrust bearing has been added to take the end thrust of the bevel gears. One of these rear-hub two-speed gears was run by the factory more than 7000 miles on the low, and micrometers could then detect no wear in the roller bearing.

AUTO-MECHANICAL OIL PUMP

Racing tests every feature of a motor severely. The Harley-Davidson automatic mechanical oil pump has been used prodigiously in races, the past few months. It is a high-pressure pump-not simply an oiler. There are no check valves, ball valves, valve springs, to stick, float or break; no small parts to go wrong. It is said to be almost as simple as the well-tested rotary breather valve. The company’s advertising matter states the technical details, an important feature of which is that “the pump is accurately adjusted at the factory, the adjustment being fixed by lock nut K. Under ordinary conditions of service no change of adjustment is necessary.”

No Under-feed; No Over-feed

Among the claims are that this pump feeds just the right amount. With oil in the tank it can neither over-feed nor under-feed. This spells oil economy, not to mention nerve economy. Also, it eliminates excessive carbonizing and the evil frills thereof. Even over-feeding wears out a motor, Chief Engineer Harley says. This over-feeding is prevented by large, positively operated valves, working independently of temperature and unaffected by different oils. This saving of over or under feeding saves not only the cylinders, but the crank pin, shafts, gears and valves. What Over-feeding Does

An interesting phase of over feeding is described. The over-feeding produces heavy oil vapor in the combustion chamber. Then the motor runs poorly. The rider adjusts the carburetor to get a richer mixture. This stunt not only rapidly deposits carbon but makes a slow-burning gas, causing overheating and loss of power. Then the rider gives ‘er more oil, which multiplies the troubles. Proper oiling, therefore, means uniform speed, power and mixture, and prolonged motor life. It eliminates fouled plugs, burned, pitted or warped valves, and so on.

There is a conveniently located hand pump, with which, after occasionally flushing the crank case with kerosene, a pumpful or two is fed into the motor. In the 1915 motors the crank case drain plug is at the side, near the motor base, making flushing simple.

The 1915 Brake Control

The brake control for 1915 is by means of a foot lever on the right foot board. The leverage obtained on the brake drum in this manner is great enough to hold the machine on the steepest hills, even with an occupied side car.

The brake is now double-acting and will hold a loaded side car in either direction. The frame construction is somewhat stronger. This, with the reinforced rear stays, makes for a materially stronger rear end construction, where side car strains are the greatest. There are several detailed refinements.

The Step-Starter

Ninety-eight per cent of alll914 Harley-Davidsons were equipped with step-starters. All the company’s 1915 machines will be so equipped. The application on the three-speed model, 11-F, is through the transmission case, but its principle is the same as on the other models. This starter was perfected years ago. No change has been found necessary, nor even suggested itself.

Additional Refinements

An illustration shows the new muffler, fastened to the frame by two nuts and detachable, for cleaning, in ltss than two minutes. Though more compact, the expansion chamber is larger. So is the tail pipe. The whole is of pressed steel. With the new muffler there is no appreciable back pressure, and the exhaust is as soft as a lover’s whisper. A new type of direct opening cut-out is operated by a foot-controlled trip.

Two Inches Lower Saddle Position

The 1915 saddle position is two inches lower-one inch due to the new frame design, the other inch through the new method of fastening the saddle at two points, which also means greater security.

For the second year, the exhaust valve springs are entirely enclosed in oil-tight sleeves. Both inlet and exhaust lifters are now adjustable, and on the new motors the intake valve housing is so fastened to the cylinder as to make an absolutely gastight fit without the use of gaskets. Roller arm studs are larger and are now ground to size. In the twins the connecting rods have a tie boss across the bottom of the forked rod, making a very rigid construction.

New Wrist Pin Lubrication

The wrist pin bearing has a new lubricating arrangement-a spiral groove distributes the oil, and a slot in the top of the wrist pin catches and retains it. On the new twin motors the breather pipe leaves the crank case at the top of the valve action housing.

Other features are, larger tool box and tool box door on the twin; larger dirt and water traps on all models; larger oil tanks and supply pipes. The oil tank, formerly between the seat mast tube and the rear mud guard on the twin, is now integral with the rest of the tank assembly, between the two upper frame tubes, on all models. The hand pump is a unit with the oil tank and its plunger is kept down by a locking device on the handle. This also prevents meddlesome Matildas from pumping the crank case full of oil, which disturbs the music of the spheres when the owner returns and discovers

Other Refinements

The priming cups are replaced by a new type of primer, in which compression leak is impossible. It has no ground joints, no springs, washers or cotter pins.

Instead of small oilers on the spring fork rocker plates there will be grease cups. On the front fork there will be a substantial lamp bracket.

The pressed-steel handle bars, by test, are more than 100% stronger than the previous construction; less weight, too; number of pieces used in their construction reduced from seven to two.

Prices, F.O.B. Milwaukee

The prices are about $10 lower on each model, than in 1914. The company states that this is made possible by increased production and production efficiency. The factory employs 700 more men than at this time a year ago. The tool-making department alone has 92 men.

Presumably, Pacific Coast prices will be about $15 higher than the factory prices stated here, as usual. The 11-B, 6 h.p. single, will be $200; 11-C, the same with two-speed, $230; 11-E, 11 h.p. twin, $240; 11-F, the same with three-speed, $275; 11-K, 11 h.p. twin, stripped stock, with standard or short-coupled frame, $250.

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