Motorcycle engine cooling system

A motorcycle comprising:

• a frame having a longitudinal axis;
• a steering assembly mounted to a front portion of the frame and pivotable with respect to the frame to steer the motorcycle;
• a front wheel rotatably mounted to the steering assembly and supporting a front portion of the motorcycle;
• a rear wheel rotatably interconnected with a rear portion of the frame and supporting a rear portion of the motorcycle;
• an engine/transmission assembly including an engine and a transmission interconnected with each other and supported by the frame, the transmission being interconnected with the rear wheel and operative in response to operation of the engine to drive rotation of the rear wheel;
• an air box mounted to the frame, the air box including an air filter, an inlet located outside of the filter and an outlet located inside of the filter such that air entering the inlet passes through the filter before exiting through the outlet;
• and
• an air box delivery system that provides air to the air box, the air box delivery system including a passage that is substantially perpendicular to the longitudinal axis and that is in fluid flow communication with the air box, the passage directing the flow of air upwardly into the air box.

A motorcycle comprising:

• a frame;
• a steering assembly mounted to a front portion of the frame and pivotable with respect to the frame to steer the motorcycle;
• a front wheel rotatably mounted to the steering assembly and supporting a front portion of the motorcycle;
• a rear wheel rotatably interconnected with a rear portion of the frame and supporting a rear portion of the motorcycle;
• an engine/transmission assembly including an air-cooled engine and a transmission interconnected with each other and supported by the frame, the transmission being interconnected with the rear wheel and operative in response to operation of the engine to drive rotation of the rear wheel;
• an engine cooling fan creating a flow of cooling air across the engine;
• and
• a thermostat measuring the temperature of the engine, wherein the engine cooling fan is operable at first and second speeds, the engine cooling fan being interconnected with and activated by the thermostat, the engine cooling fan creating the flow of cooling air at the first speed in response to the engine temperature being within a first range of temperatures and at the second, faster speed in response to the engine temperature being within a second higher range of temperatures.

A motorcycle comprising:

• a frame;
• a steering assembly mounted to a front portion of the frame and pivotable with respect to the frame to steer the motorcycle;
• a front wheel rotatably mounted to the steering assembly and supporting a front portion of the motorcycle;
• a rear wheel rotatably interconnected with a rear portion of the frame and supporting a rear portion of the motorcycle;
• an engine/transmission assembly including an air-cooled engine and a transmission interconnected with each other and supported by the frame, the transmission being interconnected with the rear wheel and operative in response to operation of the engine to drive rotation of the rear wheel;
• an engine cooling fan creating a flow of cooling air across the engine;
• a cooling air duct that substantially encloses a portion of the engine, the engine cooling fan being in communication with the cooling air duct such that the flow of cooling air is moved through the cooling air duct and across the portion of the engine to cool the engine, wherein the frame includes a left portion that partially covers the left side surfaces of the engine and a right portion that partially covers the right side surfaces of the engine, and wherein the cooling air duct is partially defined by the left and right portions of the frame;
• and
• an air box mounted to the frame above the engine, wherein the air box partially defines the cooling air duct.