The pistons are new, too, and not just because they’re bigger around. Until the V9, the small-block Guzzi engine used so-called Heron heads. Heron heads have no combustion chamber in the head itself, which is machined flat and carries the two valves (in the V7’s case) side by side, faces flat to the machined surface of the head; there’s no relative angle between. Such a design simplifies the valvetrain, which can be straight from the cam follower through the rocker arm right to the valve. In a Heron head, the combustion chamber is actually part of the piston, with each engine design using a Heron head having more or less of a depression in the head to create the desired compression ratio. Heron heads have gradually fallen out of favor with the proliferation of four-valve heads and as engineers find new ways to shape conventional combustion chambers in the heads.