Harley-Davidson's history is sign-posted by engine types. Even casual fans know the Knucklehead to Panhead to Shovehead lineage, but it's the motor that followed those classics that may be the most important. The Evolution series – "Evo" for short – has quite rightly been called the Engine That Saved Milwaukee. Introduced in 1984, just three years after a group of executives had purchased a failing Harley-Davidson from parent company AMF, the engine had to address quality-control issues that had plagued the Shovelhead design. The Evo came through. It was reliable, oil-tight and many thousands of miles more durable than its predecessor. Had the engine had teething problems and an ensuing flurry of warranty claims, it's quite likely that Harley-Davidson would not have survived. Hobday's Evolution Harley is a Low Rider model with aftermarket windscreen and air cleaner assembly, and was his daily rider.