Internal combustion engine

A four cycle internal combustion engine comprising:

• a vertically disposed cantilever crankshaft having a shaft portion and a center axis;
• a main block including a cylinder block section having an inner bore with a horizontal axis, and a crankcase half section, said cylinder block section and said crankcase half section being formed as a single body, said crankcase half section having a bearing portion for supporting said crankshaft thereon, said shaft portion of said crankshaft being supported at two points of said bearing portion, one of said points being below and near to said inner bore and the other of said points being spaced downwardly therefrom, said crankcase half section being upwardly open in a direction of said center axis of said crankshaft and also in a direction of said horizontal axis of said inner bore to define an opening which has an opening edge arranged in an inclined relationship to said center axis of said crankshaft and also to said horizontal axis of said inner bore;
• a camshaft rotatably mounted in said crankcase half section and disposed perpendicularly to said center axis of said crankshaft at a position wholly between a respective horizontal plane passing through each of said two points of said bearing portion;
• and
• a crankcase half having an inclined opening edge corresponding to said opening edge of said crankcase half section for covering said opening of said crankcase half section.