•  The cylinder head is made of a highly heat conductive, lightweight, and aluminum alloy.

•  Compact, pentroof combustion chambers have been adopted. The spark plugs are mounted at the top of the combustion chambers to improve combustion efficiency.

•  The intake/exhaust port layout is a cross flow type, (the angle between two valves is 30°, two intake valves and two exhaust valves per cylinder) which improves air intake/exhaust efficiency.

•  Knocking suppression and high pressurization are realized by the optimum shape of the intake air port.

•  The cylinder head bolts are plastic region tightening bolts, tightened in three steps to insure tightening stability.