Abstract: The present invention relates to a breather device for overhead valve engines characterized by being provided with a breather chamber arranged on the side of a cylinder or crank chamber, a push rod chamber formed on the side of and integrally with said cylinder or crank chamber and a cylinder head and making the periphery of each push rod housed within it a blow-by gas passage connecting the above mentioned crank chamber with a rocker chamber and a blow-by gas discharging passage connecting the above mentioned rocker chamber and breather chamber with each other, whereby the pressure fluctuation within the crank chamber can be utilized to utilize the ventilating action of a one-way breather valve, to thereby lubricate the rocker chamber, to need no oil pump and to reduce the cost and the rigidity of the cylinder including the crank case and of the cylinder head can be elevated.

Abstract: The present invention is to provide a cylinder head for air-cooled engines wherein a part of the top wall is depressed to form a rocker arm chamber and a cooling wind passage reaching the upper part of a suction port from the side of an exhaust port is formed between the bottom wall of the rocker arm chamber and the upper wall of a cylinder fitting surface, whereby the advantage of the performance of a conventional overhead valve engine is retained as it is, the defect of the increase of the height is kept as little as possible and the cooling performance is not reduced.