Introduced in 1915, the 61ci (1000cc) F-head was big step forward for Harley and would remain in the lineup until 1929. It established the 45-degree V-twin as the brand's trademark powerplant. Chassis-wise, we see the beginnings of streamlined styling in the rounded corners of the gas tank, which also has the familiar clearance pockets for the valve mechanisms. Gone are the starting pedals held over from the bicycle era, replaced with a proper kickstarter. Of note is the three-speed gearbox, and a 61 was the first Harley to be equipped with electric lighting, though as shown here many riders still preferred tried-and-true acetylene over newfangled electrons. The motor was improved for 1917 with a four-lobe camshaft and enclosed intake valve springs. Buyers could choose between the Model J with a battery and coil ignition or the Model F with a magneto.

The Hobday collection's 1917 Model F, an older restoration, is finished in the olive paint that would be standard on the Milwaukee machines for many years, nicely contrasted by nickel-plated metal pieces. It's also equipped with a "Full-Floeting" seat wearing the proper spring sheaths introduced that year, and is fitted with a hard-to-find tire pump clipped to the rear frame rail. Speedometers were still optional and the rider of this F could only guess at the bike's top speed, about 65 mph. An important piece of America's motorcycling history, the bike appears to be a simple recommissioning away from being fully road-ready.