In the Middle Ages of motorcycling, British 650cc parallel twins used to be the hot setup. You found them everywhere, ruling the street, racing at Ascot and Daytona, and even in the desert. That is, until Japanese bikes grew up; then it was game over. But this likable twin-cylinder formula has risen from the ashes with the Kawasaki Z650. The heart of a motorcycle is naturally its motor, and the Z650’s displaces 649cc with a short-stroke design that contributes to high-revving, energetic performance that the 1960s and ’70s street twins could only dream about.