Cooling system for V-shaped, forced air-cooled engine

Claim 1

A cooling system for a V-shaped, forced air-cooled engine, said engine including a crankcase, and first and second cylinders mounted in V form on top of the opposite sides of said crankcase, said cooling system including: a radial flow cooling fan mounted on the front of said crankcase, and driven by said engine to rotate in a direction from said second cylinder toward said first cylinder; a fan housing covering said fan and at least the front portions of said cylinders, said housing including first and second cooling air passageways arranged to pass cooling air from said fan to said first and second cylinders, respectively; means within said housing defining a first threshold wall area at the downstream side of the first passageway, and a second threshold wall area at the downstream side of said second passageway; said first passageway having a first threshold point disposed on said first threshold wall area generally in line with the downstream side of said first cylinder, said second passageway having a second threshold point disposed on said second threshold wall area generally in line with the downstream side of said second cylinder but slightly biased towards said fan, a third threshold point being disposed under said fan, the angle measured between a first line extending from said first threshold point and the center of said fan and a second line extending from the center of said fan to said second threshold point being substantially the same as the angle measured between said second line and a third line extending from said center of said fan to said third threshold point; and said first and said second threshold wall areas, in the regions of the threshold points, being rounded, slow curves, being generally obtuse and being free of any protuberances, projections, nubs or sharply bending turns.