PROCESS FOR FORMING EXHAUST SECONDARY AIR PASSAGE AND STRUCTURE OF SAME

摘要

PROBLEM TO BE SOLVED: To simplify machining of a secondary air feeding passage. SOLUTION: A secondary air feed passage 41 for communicating an exhaust port 8 of a crank case with a reed valve chamber formed on a cylinder head cover 4 is composed of a secondary air feed passages 41a for a cylinder head 3, a secondary air feed passage 41b for a cam holder 42, and a secondary air feed passage 41c for a cylinder head cover 42. The secondary air feed passage 41a is formed normal to a gasket 45 and is communicated through the exhaust secondary air introducing portion 46 with its leading end integrally formed using a core of the exhaust port 8 during casting of the cylinder head 3.