Patent ID: 8667946

Claim:
A multi-cylinder engine comprising: a cylinder block including a plurality of cylinder bores; an upper crankcase and a lower crankcase that form, in combination, a plurality of crank chambers corresponding to the cylinder bores; a bulkhead that partitions between the cylinder bores and the crank chambers adjacent to each other; and a honing release portion having a cylindrical honing release surface formed continuously with the cylinder bore in the upper crankcase and the bulkhead, wherein the cylinder block and the upper crankcase are formed integrally, the honing release surface is formed with a diameter larger than the cylinder bore, and an arcuate recessed portion is formed in the bulkhead, the bulkhead is formed with a communication hole that communicates with the crank chambers adjacent each other, the bulkhead including a first opening edge on a side of the cylinder bore extending in a direction substantially perpendicular to a cylinder axis, a second opening edge on a side of the crank chamber having an opening width decreasing with a distance from the cylinder bore, and a third opening edge that extends substantially in parallel with the cylinder axis and connects between the first opening edge and the second opening edge, and the second opening edge is formed from the cylinder bore to the recessed portion to prevent the honing release surface from being divided.