An internal combustion engine (10) fitted with a carburetor (40) is provided with a fire-resistant cover member (62) having a front wall (65A) facing an air inlet port (44) of the carburetor, and a breather tube (60) having an inlet end (60A) connected to a crank chamber (28) of the internal combustion engine main body, and an outlet end (60B) supported by the cover member at a position located between the front wall and the carburetor.

An internal combustion engine (10) fitted with a carburetor (40) is provided with a fire-resistant cover member (62) having a front wall (65A) facing an air inlet port (44) of the carburetor, and a breather tube (60) having an inlet end (60A) connected to a crank chamber (28) of the internal combustion engine main body, and an outlet end (60B) supported by the cover member at a position located between the front wall and the carburetor.

A method of setting a tappet in an engine. The method includes setting a crankshaft at a predetermined crankshaft rotation angle. A cam coupled to the crankshaft is configured to provide cam lobe lift when the crankshaft is set at the predetermined crankshaft rotation angle. The cam lobe lift translates a tappet screw, coupled to the cam, towards a valve by a distance less than a gap defined between the valve and the tappet screw. The method also includes adjusting the tappet screw such that a zero gap tappet clearance is defined between the valve and the tappet screw.

A blow-by gas inlet structure of an oil separator adapted to be placed above a cam chamber of an internal combustion engine, comprises a plate that forms a bottom wall of the oil separator; a blow-by gas inlet opening that is formed in the plate; an oil blocking structure that is provided below the blow-by gas inlet opening in a manner to divide the blow-by gas inlet opening into front and rear inlet openings through which the blow-by gas is led into the oil separator, the front and rear inlet openings being arranged in a first direction; and a transverse rib that is provided on the oil blocking structure and extends in a second direction that is perpendicular to the first direction.

In an auxiliary chamber gas supplying device for a gas engine including an auxiliary chamber gas supply path (5, 14, 28, and 29) through which fuel gas is supplied to an auxiliary chamber (4), the auxiliary chamber gas supply path is connected to a fuel gas supply source (24) through a solenoid valve (23), and when the solenoid valve is opened, the fuel gas, in an amount corresponding to an opened period of the solenoid valve, is supplied from the fuel gas supply source to the auxiliary chamber through the auxiliary chamber gas supply path, and the opened period of the solenoid valve is set in such a manner that a predetermined amount of fuel gas is supplied to the auxiliary chamber, and a restriction unit (30) that extends the opened period of the solenoid valve is formed in the auxiliary chamber gas supply path (5, 14, 28, and 29).