Structure of overhead-valve internal combustion engine and manufacturing method for the same

摘要

In order to supply a sufficient quantity of lubricating oil to the entire valve operating mechanism, we designed a lubrication device for an overhead valve engine. A first breather passage goes from the valve operating mechanism chamber to the crankcase, passing through the cylinder head and cylinder. The first breather passage opens in the vicinity of the spring retainer for the intake valve on the surface of the cylinder head which faces the valve operating mechanism chamber for the valve operating mechanism. The opening of the first passage and the vicinity of the exhaust valve are connected by a second breather passage. This second passage comprises a groove formed by cutting in the valve operating mechanism chamber surface of the cylinder head, and a tunnel formed between an oil guide wall which goes up from the valve operating mechanism chamber surface of the cylinder head and the peripheral wall of the head. One end of this groove connects to the opening of the first breather passage.