system. Note the screw caps in the cylinder heads giving access to the valves. Harley-Davidson's intention in introducing a new middleweight model was to increase the size of the motorcycle market by appealing to new riders with an entry-level product. The design imitated the British
Douglas motorcycle flat-twin with cylinders in line with the frame, and offered several features that were meant to bring new motorcyclists into the market, including a smoother running engine than a typical Harley-Davidson
V-twin, a lower center of gravity for easier handling, and a design that kept the rider and the motorcycle cleaner from oil and the dirt that oil attracted. It was cleaner because there were fewer oil compartments, due to the
transmission and
clutch being
integrated with the engine
crankcase, providing fewer ways for the oil to leak. In addition, an optional drive chain enclosure could keep chain lubricant off the motorcycle and the rider's clothing.
Drivetrain The engine components were designed for ease of access and maintenance. The valve guides and valves could be removed without removing the engine from the motorcycle. The cylinder heads were
integral with the engine. The intake and exhaust manifolds were cast as one piece such that the exhaust would heat the fuel mixture to improve fuel atomization. The engine had a large external flywheel on the left side similar to that on the horizontal single-cylinder Moto Guzzi. The Model W engine was Harley-Davidson's first
flathead engine, and its transmission was the first in a Harley-Davidson motorcycle to be
housed in the engine cases. The transmission included helical gear drive, a wet clutch, and a three-speed gearbox. The engine was a
stressed member of the frame.
Suspension The front suspension was by a
trailing-link fork, unlike those on other Harley-Davidsons, which used
leading-link forks at the time.
Electrical system and ignition The Model W initially used a magneto-powered ignition system, but a battery and coil system became available with the Model WJ in 1921. The Model WF continued with magneto ignition. Electric lighting became available on the Model W in 1920.
Accessories and trim The Model W had a standard luggage carrier on the rear fender. In 1921, the tank logos were changed to be similar to those on Harley-Davidson's larger V-twin motorcycles. ==Endurance records==