 The "650" refers to the engine displacement.In 1999, superseding the Zephyr series, Kawasaki introduced the W650, resembling British motorcycles of the early 1960s, notably the Triumph Bonneville.In contrast to British twin-cylinder motorcycles of the period, which featured pushrod engines, the W650 features a shaft-driven bevel-gear overhead camshaft, similar to those found on 1970s Ducati singles and V-twins.