Disclosed is a structure of cylinder head (52) of air cooling engine (3). The cylinder head (52) forms a longitudinal channel (7) between a valve driving member (522) and a combustion chamber (523) and extending completely therethrough in a direction of an...

An internal combustion engine 10 mounted on a motorcycle has a forward-tilted or substantially horizontal cylinder and is provided on its upper surface with a cooling fin structure 31 including cooling fins 30 extending in a direction in which the motorcyc...