Abstract: An air intake system for an internal combustion engine has a vertical crankshaft and a pair of substantially horizontally disposed cylinders that extend outward from a crankcase to form a V-space therebetween. The air intake system includes an air inlet through a blower housing on top of the engine, an air cleaner housing that is disposed substantially directly above the V-space and that receives air from the air inlet, an air-fuel mixing device disposed substantially directly below the air cleaner, and an intake manifold adapted to deliver a combustible mixture from the air-fuel device to each cylinder. The air cleaner includes a filter supported such that air received from the air inlet flows through the filter in a substantially upward direction. The air cleaner housing and the blower housing are integrated into a single housing.