Why Harley-Davidson’s Switch To V-Twins Was Harder Than Just Adding One other Cylinder

Harley-Davidson has been constructing and selling motorcycles for over 120 years. But the primary bikes, and the way William Harley and Arthur Davidson built them, are far cry from how the Motor Company does things today. The 2 built a tiny wood shack in Milwaukee in 1903, no larger than a typical one-car garage. It was in that shack that William, Arthur, and Arthur’s brother, Walter Davidson, set to work constructing motorcycles. But they didn’t start by slapping a V-Twin right into a chassis. No, they began with single-cylinder bikes.

In 1909, the Harley-Davidson Motor Company took a stab at its first V-Twin. In order that’s it, right? The corporate’s first two-cylinder applications were an quick hit, and the Motor Company was off to the races? 

Not quite. In actual fact, Harley-Davidson’s first attempt at a 45-degree twin didn’t work quite right. Because it seems, making the shift from single-cylinder bikes to the V-Twins that will ultimately define the brand and provides Harley-Davidsons their distinctive sound wasn’t easy.

Let’s get one thing straight: The one-cylinder bikes weren’t a flop. In any case, the brand’s 35-cubic-inch single carried Walter Davidson to victory in a 1908 endurance run and even netted an economy record. But it surely didn’t take long for William Harley to understand that the one-pot engines would not sustain with the buyer’s demand for more power. So he concluded that adding one other cylinder to the combination was the very best plan of action. One is sweet, so two should be higher, right?

Here’s the thing, though: Adding a cylinder presented a brand new problem. The brand new 7-horsepower V-Twin within the 1909 5-D Twin used an atmospheric intake-over-exhaust application. Within the previous single-cylinder applications, atmospheric inlet valves operated by utilizing suction created by the operation of the solitary piston. Using a retreating piston to suck a valve open had worked well with singles, but not a lot with the brand new 5-D “F-head” twin.

The additional volume (two cylinders at 49 cubic inches in comparison with the only’s 35 cubic inches) reduced that suction’s effectiveness and kept the valves from operating properly. There was a probability Harley-Davidson could have remedied the issue, however the team went a special route. As an alternative of trying to alter things up for the F-head bikes, the MoCo recalled every one in every of the 27 it was reported to have built with the early twin and destroyed them.

It didn’t take long for Harley-Davidson to enhance after the 5-D’s design flaws. By 1911, the brand rolled out an improved Model 7-D twin. Having learned from the 5-D’s finicky valve operation, the brand new 7-D F-head featured pushrod-operated mechanical valves, still in an inlet-over-exhaust layout. Gone was the problem with the atmospheric inlet valves. Finally, Harley had a scalable V-Twin with which to extend displacement and sustain with consumer demands for increased power output. And that is exactly what the Wisconsinites did.

Within the years that followed, the motorcycle builder increased the F-head V-Twin’s displacement to 61 after which 74 cubic inches. But time stops for nobody, not even the corporate’s then-successful F-head twin. By 1929, Harley-Davidson had its substitute: the Flathead. Adopting a side-valve layout and a set of characteristic flat cylinder heads, the Flathead powered the brand’s products for over 4 many years, from 1929 to 1973. 

However the Flathead was removed from alone. Over time, Harley-Davidson would proceed to work on improving the V-Twin on its solution to the most recent Milwaukee-Eight engines, adding features like overhead-valve construction, electronic fuel injection, and even high-horsepower, liquid-cooled applications with Porsche power. But it surely all began with a troubled transition from a single to a twin.