A preformed article 10A, for a cylinder head, includes: a first portion 11 where a first through hole 15 is to be formed from an upper wall portion 18 to a central portion 19a which is a portion, of a bottom wall portion 19, forming a combustion chamber of...

The engine has a cylinder crank case (1), in which a piston, a piston rod and a crank shaft are integrated. An inlet duct with an inlet valve, an exhaust duct with an outlet valve and a fuel injection valve are provided in cylinder heads. The heads with tw...