64 The 1914 Model 10-F is the only model to feature H-D’s first transmission. Patented by William S. Harley, it features two speeds located in the rear hub. It added yet another dose of rider friendliness to the early machines. At least, that was the idea. The bicycle-style epicyclical rear hub was so revolutionary, and had such tight tolerances, that many riders found it difficult to operate. A company service bulletin was published that reminded 10F owners not to force the shifter into gear when the machine wasn’t running, which could cause the shift lever to bend. The 10-F also saw the first use of floorboards and a pedal-operated drum brake in the rear.
65 The Harley-Davidson motorcycle took a major stride forward with the 1915 11-F and the introduction of the 3-speed, sliding-gear transmission that sits behind the engine. The new 3-speed featured large ball bearings to secure the main shaft; two special, heavy-duty roller bearings allow the jackshaft to spin smoothly. The jackshaft transmits power in low and intermediate gear while the transmission is essentially free running in high gear. For extra durability, the engineers made sure not to include any small parts that could potentially break or wear out, and the 3-speed proved to be extremely reliable. The transmission is controlled with a foot-operated rocker clutch and a gated shift arm on the tank. With 9,855 produced, 3-speed H-Ds made up 75 percent of that year’s total motorcycle production. The 1915 11-F is, like the 10-F before it, a one-year-only design thanks to its using bicycle-style pedals to start the engine.
The Motor Company’s 1915 model 11-F set the stage for every Big Twin to follow with its durable 3-speed transmission, a powerful V-twin, and an automatic oil pump, which is visible on the gearcase. By using a separate engine and transmission, linked only by the primary chain, this setup would last for another 80 years on some Big Twin models.
66 In addition to the new 3-speed transmission, Harley-Davidson completely redesigned its 61-ci IOE engine for 1915. It now used larger intake valves that now entered the heads at a 45-degree angle instead of a 60-degree angle. The engine used new cylinders and a larger intake manifold to increase airflow. To handle the power increase, engineers used heavier flywheels with a 1-inch crankpin (previously 7/8 inch). The new Harley-Davidson–made bearings are 3/8 inch wider than on the previous engine. A newly designed, more efficient muffler was used and, while it produced significantly less backpressure, it also made less noise.
67 The engine lubrication system was also completely reimagined in 1915, beginning with the oil tank’s relocation from underneath the seat to the left side of the gas tank; it now displaced 2-1/2 quarts. A new, automatic oil pump, visible on the cam cover on the right side of the engine, ensured precise lubrication at any speed and crank pressure. Occasionally, when running flat out, or powering up a steep incline, the rider had to pump in extra oil via the auxiliary hand pump that sat atop the oil tank.
68 Harley-Davidson claimed exactly 29 engine improvements, leading the 1915 models to put out an advertised 31 percent more power at 2,500 rpm and a whopping 47 percent more power at 3,000 rpm. The Motor Company guaranteed that the 11-F was capable of achieving 65 mph. My friend and colleague, Cris Sommer Simmons, can vouch for that claim; she rides her 1915 11-F regularly (and rode it more than 3,000 miles on the 2010 Motorcycle Cannonball).
69 In 1915, The Motor Company guaranteed the 61-ci V-twin to produce 11 hp. Solid output on these early machines, no doubt, but just because the company guaranteed it, didn’t make it so. In fact, in typical Harley fashion, 11 hp was a modest figure, and many of its street engines actually produced up to 16 hp on the dynamometer thanks to larger intake and exhaust ports, which lead to larger valves and carburetors.
70 With the sliding-gear transmission in 1915 also came the first use of the gated shift lever on the left side of the gas tank. The gate is labeled with the different gear positions so the rider can easily and confidently put his motorcycle into the correct gear. The 1915 gate is mounted to the left-side oil and gas caps and is notched to make it more difficult to go back a gear by mistake.
71 Some riders today have trouble stopping and starting on a hill. So imagine what it was like for riders in 1915 when they were learning to use a clutch and transmission for the first time, and didn’t have a front brake to hold. To alleviate this issue, a rider could engage and disengage the clutch with his or her left hand using a lever attached to the clutch pedal linkage. The rider kept the left foot on the ground to stabilize the bike with the right foot on the pedal brake. Then he (or she) used the throttle with the right hand as usual while releasing the clutch with the left hand. Off and away!
72 Although readers of this book probably like to argue that Harley-Davidson built (and still builds) the best motorcycle engine available, it wasn’t the first. All early motorcycle engines stemmed from a single design created by Frenchmen Albert de Dion and Georges Bouton in the 1890s. Every other IOE motorcycle engine produced at the time, whether by Indian, Harley-Davidson, or Merkel used a nearly identical design as the de Dion-Bouton engine. This is important to The Motor Company’s history because without the de Dion-Bouton, motorcycling might have gotten off to a later and less successful start.
73 If you measure the rear belt drive pulley on a modern Harley, you’ll find it’s about 9 inches in diameter and, as you already know, supplies a solid mix of off-the-line acceleration and on-highway cruising performance. In Harley-Davidson’s early days, before transmissions and when belt-drives were still a leather strap with no teeth, the rear wheel pulley measured 20 inches in diameter. It provided enough force to get the single-cylinder machine moving. As with many drive belts today, the original leather belt was 1.25 inches wide on the singles and 1.75 inches wide on the twins.
74 Today’s spark plugs are so small and inexpensive that many riders opt to keep a spare set in their tool kit at all times. But when the first Harley-Davidson was built, spark plugs were much larger (like a doorknob), and much more expensive. The first motorcycle used a spark plug that took up much of the cylinder head, and cost $3, or approximately $80 in today’s money. Considering that the earliest machines sold for about $200, that single spark plug was nearly 2 percent of the cost!
75 Some folks may wonder exactly how the early atmospheric valve system worked on the early Harleys. Keep in mind that the IOE design positioned the intake valve at the very top of the engine and the exhaust valve on the side. A camshaft and pushrod operated the exhaust valve, but the early H-D engines had no such pairing for the intake valve. Instead, as the piston went down in the cylinder on the intake stroke, that vacuum caused the valve to be pulled down into the cylinder head, allowing air and fuel to enter. Then, on the compression stroke, the upward motion of the piston forced the valve shut. The explosion on the power stroke created enough pressure to keep the valve closed; on the exhaust stroke, the piston forced pressure back up again.
76 Janet Davidson, the older sister of the brothers, was responsible for the famous hand-painted “HARLEY-DAVIDSON MOTOR CO.” on the front door of the famous backyard woodshed where the first motorcycles were built. She’s also responsible for the lettering and pinstriping on the early motorcycles. In the very early days, their other sister, Elisabeth, was in charge of the company’s bookkeeping.
77 Although the first Harley-Davidsons were painted black, Henry Ford quickly laid claim to that color, and the founders wanted their machines to stand apart from other machines. Renault Gray was chosen as their official color because it blended in so easily with the streets and surroundings of the early 1900s. Black was still available until 1910. And most riders, especially H-D’s target customer (the working man), didn’t want anything flashy or showy. Early Harleys also had the reputation of running more quietly than other brands,