Claim: The DOHC Genesis engine has five valves per cylinder as Yamaha adopted the 5-valve concept because it allowed both excellent volumetric efficiency and high rpm.
Evidence: The DOHC Genesis engine has five valves per cylinder and downdraft carburetors. Yamaha adopted the 5-valve concept, using three intake valves and two exhaust valves per cylinder, because it allowed both excellent volumetric efficiency and high rpm.