Cylinder Material: Ceramic plating Displacement: 138cc Bore Diameter: 59mm Compression ratio: 13.0:1 Included Camshaft: S-20D Intake Valve Diameter: 30mm Exhaust Valve Diameter: 24.5mm Valve Stem Shaft Diameter: 4.5mm for both IN and EX [Set components] ・Super Head + R Head Kit ・Cylinder Kit ・Camshaft