The valves are larger and the pistons are new." Roy Lunn recalled, "We wanted as much displacement - for power and torque - as possible within the confines of bore centers of the tooling.
Roy Lunn stated that the valves were bigger, and the pistons were replaced with newer ones. They wanted as much engine displacement as possible, focusing on both power and torque, but they had to work within the limits of the tooling used for the cylinder bores.