head 18 and the cylinder head cover 20 fig4 referring to fig2 4 the cylinder head 18 includes a top or first surface 26 a bottom or second surface 28 a front face 30 a rear face 32 and first and second side faces 34 36 the cylinder head 18 is fastened to the cylinder housing 16 such that a gasket 38 is coupled between a planar portion 40 of the bottom surface 28 and a corresponding planar portion 42 of the cylinder housing 16 the planar portion 40 of the bottom surface 28 defines a base plane 44 the cylinder head 18 is fastened to the cylinder head cover 20 such that a planar portion 46 of the top surface 26 of the cylinder head 18 is in contact with a corresponding planar portion 48 of the cylinder head cover 20 referring specifically to fig3 the cylinder head 18 further includes an intake port 50 that extends through the cylinder head 18 from the rear face 32 to the bottom surface 28 to communicate with a combustion chamber 51 the intake port 50 includes a straight portion 52 that projects downwardly from the rear face 32 and a curved portion 54 that smoothly transitions from the straight portion 52 to the bottom surface 28 and the intake valve seat 74 the curved portion 54 is preferred but is not necessarily required.