Patent ID: 7086367

Claim:
An air flow arrangement for a reduced-emission, single cylinder engine, the arrangement comprising: an engine housing; an intake opening positioned on a first side of the engine housing; an exhaust opening positioned on a second side of the engine housing adjacent the first side; an inlet crossover passageway for introducing intake air to the engine, the inlet crossover passageway drawing intake air from a location disposed from the second side; an intake passageway defined in the engine housing downstream of the intake opening, the intake passageway including an intake runner downstream of the intake opening and an intake port downstream of the intake runner such that an intake valve is positioned in the intake port, the intake port having a substantially conical shape to increase flow efficiency of the intake air through the intake passageway; and an exhaust passageway defined in the engine housing upstream from the exhaust opening, the exhaust passageway including an exhaust runner upstream of the exhaust opening and an exhaust port upstream of the exhaust runner such that an exhaust valve is positioned in the exhaust port, the exhaust runner having a substantially conical shape to increase flow efficiency of exhaust gases through the exhaust passageway.