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block. It contains valves that open and close to allow the fuel charge to get in and the spent exhaust gases to get out. Motorcycle engines can have anywhere from two to five valves per cylinder. Most Harleys have two valves per cylinder: one intake and one exhaust. Victory motorcycles all have four valves: two intake valves and two exhaust valves. Some Hondas have three valves per cylinder, and a handful of Yamahas had five valves per cylinder, but most modern motorcycles will have four valves per cylinder.
    With very few exceptions, the fuel-air charge is injected by electronically controlled atomizers on modern motorcycles, though there are still a few good used bikes out there that have old-fashioned carburetors mixing the fuel-air charge and getting it into the combustion chamber. Triumph recently switched from carburetion to fuel injection on its Bonneville-series twins, and these bikes had been some of the last new models to feature carburetors.
    THE FOUR STROKES OF A FOUR-STROKE
    F OUR-STROKE ENGINES ARE CALLED four-strokes because each cycle of the combustion process consists of four strokes of the piston. The first (downward) stroke is called the “intake stroke” because the intake valves open on this stroke and the downward-moving piston draws in the fuel-and-air charge. The second (upward) stroke is called the “compression stroke” because the upward-moving piston compresses the fuel-air charge, which is ignited very near the top of the compression stroke (called “top dead center,” or TDC). The energy generated by this ignition is called “combustion,” and it’s what gives its name to the third (downward) stroke, the combustion stroke (also called the “power stroke”). The fourth (upward) stroke is called the “exhaust stroke” because the exhaust valves open on this stroke, allowing the upward-moving piston to force the spent exhaust gases out through the open valves.
    REDLINING
    I’ M NOT A HUGE fan of Harley-Davidson motorcycles. That is partly because for many years Harley sold motorcycles that were worn-out antiques even when they were new. In 1969 AMF (American Machinery and Foundry) bought Harley. By that time the Japanese had begun to introduce motorcycles with modern technology, and in the following years the pace of development of motorcycle technology quickened. When AMF sold Harley in 1981, the motorcycles coming from Japan were so highly developed that they made the motorcycles they produced in the 1960s look like antiques.
    The bikes Harley built between 1969 and 1981 had barely changed; if anything, they got even worse. AMF looked at Harley as a cash cow and milked it dry. The company put very little money into product development. Instead, AMF ramped up production so that besides selling antiquated motorcycles, Harley’s quality control went down the toilet; not only were Harley’s motorcycles handicapped with old-fashioned technology like cast-iron engines, but they also became increasingly unreliable.
    It wasn’t that way when I started riding. In the 1950s all but the most expensive high-performance motorcycles had cast-iron engines and Harleys were as good as or better than any other bike on the market. But within fifteen years the Japanese, German, and Italian manufacturers were selling motorcycles with aluminum cylinder blocks almost exclusively. Besides Harley, only the British still used cast iron for their cylinder blocks, and it didn’t work out too well for them: by the early 1980s the entire British motorcycle industry had gone bankrupt. In fact, the British motorcycle industry would have gone out of business many years earlier if the UK government hadn’t propped it up for the last twenty years of its existence.
    Harley almost died at the same time. The Motor Company continued to build bikes with cast-iron cylinder jugs until the mid-1980s, when the aluminum Evolution engine hit the market. Because it is important to me as a patriot to ride an American