A motor engine having an oxygen sensor is provided, including: a cylinder head, including a main body and a protruding tube protruding outwardly from the main body, the main body including a first end portion, a second end, and a combustion chamber, the protruding tube having a protrusive receptacle protruding outwardly therefrom, the main body defining an axial direction; an exhaust passage, communicated with the combustion chamber and the protruding tube; an oxygen sensor, inserted into the protrusive receptacle, including a sensing portion which is inserted into the exhaust passage; wherein as viewed in a lateral direction of the cylinder head, two surfaces of the main body along the axial direction disposed on two opposite sides defines two boundary lines, the oxygen sensor and the main body are in an overlapping arrangement and does not protrude out of the two boundary lines.

A motor engine having an oxygen sensor is provided, including: a cylinder head, including a main body and a protruding tube protruding outwardly from the main body, the main body including a first end portion, a second end, and a combustion chamber, the protruding tube having a protrusive receptacle protruding outwardly therefrom, the main body defining an axial direction; an exhaust passage, communicated with the combustion chamber and the protruding tube; an oxygen sensor, inserted into the protrusive receptacle, including a sensing portion which is inserted into the exhaust passage; wherein as viewed in a lateral direction of the cylinder head, two surfaces of the main body along the axial direction disposed on two opposite sides defines two boundary lines, the oxygen sensor and the main body are in an overlapping arrangement and does not protrude out of the two boundary lines.

A motor engine having an oxygen sensor is provided, including: a cylinder head, including a main body and a protruding tube protruding outwardly from the main body, the main body including a first end portion, a second end, and a combustion chamber, the protruding tube having a protrusive receptacle protruding outwardly therefrom, the main body defining an axial direction; an exhaust passage, communicated with the combustion chamber and the protruding tube; an oxygen sensor, inserted into the protrusive receptacle, including a sensing portion which is inserted into the exhaust passage; wherein as viewed in a lateral direction of the cylinder head, two surfaces of the main body along the axial direction disposed on two opposite sides defines two boundary lines, the oxygen sensor and the main body are in an overlapping arrangement and does not protrude out of the two boundary lines.

A small air-cooled internal combustion engine includes an aluminum engine block including a cylinder extending along a longitudinal cylinder axis and a block mounting surface, a piston configured to reciprocate within the cylinder, a crankshaft coupled to the piston and configured to rotate about a crankshaft axis in response to reciprocation of the piston, and an aluminum crankcase cover including a cover mounting surface. The block mounting surface contacts the cover mounting surface. The block mounting surface and the cover mounting surface are both positioned at an angle to the crankshaft axis and the angle is not 90 degrees.

A cylinder head and push rod tube configuration for an internal combustion engine is disclosed. The cylinder head includes a first end comprising a recessed rocker arm cavity. The cylinder head also includes a second end opposite the first end and defining an upper end of a combustion chamber. The recessed rocker arm cavity has a lower surface with a pair of push rod tube bores therethrough. The second end of the cylinder head has a pair of push rod tubes positioned in the push rod tube bores between the recessed rocker arm cavity and the second end. An intake port and an exhaust port each extend through the cylinder head to the combustion chamber.

A cylinder head and push rod tube configuration for an internal combustion engine is disclosed. The cylinder head includes a first end comprising a recessed rocker arm cavity. The cylinder head also includes a second end opposite the first end and defining an upper end of a combustion chamber. The recessed rocker arm cavity has a lower surface with a pair of push rod tube bores therethrough. The second end of the cylinder head has a pair of push rod tubes positioned in the push rod tube bores between the recessed rocker arm cavity and the second end. An intake port and an exhaust port each extend through the cylinder head to the combustion chamber.