Crank chamber communication structure of multi-cylinder internal combustion engine

A crank chamber communication structure for a multi-cylinder internal combustion engine having a plurality of partition walls that are formed in a cylinder block that forms a plurality of three or more, cylinders, each of which houses a piston, and in a crankcase, which is fixed to the cylinder block, the partition walls are formed to support a crankshaft and to define a plurality of crank chambers that correspond to the plurality of cylinders, the crank chamber communication structure comprising:

• a plurality of respective first communicating holes formed in the plurality of partition walls for communication between respective pairs of adjoining crank chambers separated by an interposed partition wall;
• and
• a second communicating hole that is formed at least either of the cylinder block or the crankcase, that is interposed between a first pair of non-adjoining crank chambers between which at least two partition walls among the plurality of partition walls are interposed, and combined with a pipe that passes through at least the two partition walls that are interposed between the first pair of non-adjoining crank chambers so that the second communication hole directly connects between the first pair of non-adjoining crank chambers.