Four-cycle overhead valve engine

Abstract

To provide a four-cycle overhead valve engine wherein the breather passage is defined to avoid an undesirable increase in size of the engine as a whole and also to avoid increase in length of the breather passage, a four-cycle overhead valve engine is provided which includes a cylinder block (6), and push rods (16 and 17) for driving intake and exhaust valves (14 and 15), respectively, that are mounted above the cylinder block (6). A breather passage (28) connecting a crank chamber (27) and a rocker arm chamber (31) with each other is made up of a first passage portion (28A) defined in the wall of the cylinder block (6) at a location adjacent a flywheel (9) and the push rods (16 and 17), and a second passage portion (28B) extending from one side adjacent the push rods (16 and 17) in a direction away from the push rods (16 and 17). A check valve (34) for the breather passage (28) is disposed at a junction between the first and second passage portions (28A and 28B).

Dependencies are inferred from the claim text.