An improved internal combustion engine air intake system that operates in tandem with the original equipment air intake system and does not endanger the vehicle warranty and provides improved airflow to the engine which improves engine performance and efficiency. The improved internal combustion engine air intake system also provides one or more additional air inputs taken from a different location than the original equipment air intake which improves the likelihood of providing additional cooler, denser, air to the engine air intake which will improve engine efficiency.

An improved internal combustion engine air intake system that operates in tandem with the original equipment air intake system and does not endanger the vehicle warranty and provides improved airflow to the engine which improves engine performance and efficiency. The improved internal combustion engine air intake system also provides one or more additional air inputs taken from a different location than the original equipment air intake which improves the likelihood of providing additional cooler, denser, air to the engine air intake which will improve engine efficiency.

One embodiment of the invention relates to an internal combustion engine including an engine block having a first cylinder and a second cylinder, a crankshaft configured to rotate about a crankshaft axis, a flywheel coupled to the crankshaft, a throttle body, an air filter assembly, a first electric fan coupled to a first duct, and a second electric fan coupled to a second duct. The first duct is configured to direct cooling air directly over the first cylinder. The second duct is configured to direct cooling air directly over the second cylinder. The first cylinder is at least partially within the first duct. The second cylinder is at least partially within the second duct.

A two-wheeled vehicle includes a frame having a front frame portion, a mid-frame portion, and a rear frame portion. The mid-frame portion is coupled to the rear frame portion and the front frame portion. The vehicle further includes a plurality of ground-engaging members for supporting the frame. The engine includes an air deflector to assist in cooling a rear cylinder of a V-twin engine. An accessory windshield is also shown which may be coupled to the handlebars and front forks of the vehicle. Also, a rear accessory attachment is shown mountable to the rear fender.

A filter element has, on a filter element housing, a first and a second filter medium body, which are arranged at an angle to each other.

A combustion air filtration apparatus for filtering combustion air for an engine is disclosed. The combustion air filtration apparatus comprises a combustion air source and a filter system fluidly coupled to the combustion air source and to the engine to receive combustion air from the combustion air source and to supply filtered combustion air for the engine. The filter system comprises a first combustion air filter, a second combustion air filter flow-parallel to the first combustion air filter, and a flow control system fluidly coupled to the first combustion air filter and the second combustion air filter to direct flow of combustion air selectively between the first combustion air filter and the second combustion air filter.

One embodiment of the invention relates to an internal combustion engine including an engine block having a first cylinder and a second cylinder, a crankshaft configured to rotate about a crankshaft axis, a flywheel coupled to the crankshaft, a throttle body, an air filter assembly, a first electric fan coupled to a first duct, and a second electric fan coupled to a second duct. The first duct is configured to direct cooling air directly over the first cylinder. The second duct is configured to direct cooling air directly over the second cylinder. The first cylinder is at least partially within the first duct. The second cylinder is at least partially within the second duct.

A multi-cyclone separator of a multi-stage fluid filter for cleaning gaseous fluid is provided with a plurality of cyclone cells for separating particles and/or liquid from the gaseous fluid. The cyclone cells each have an inlet for the gaseous fluid to be purified, an outlet for the gaseous fluid freed of particles and liquid, and at least one discharge window discharging the separated particles and liquid. At least one discharge chamber is provided, and the discharge windows of the cyclone cells open into the at least one discharge chamber. At least one discharge opening leads out of the at least one discharge chamber. The at least one discharge chamber tapers in a funnel shape toward the at least one discharge opening. A multi-stage fluid filter is provided with the multi-cyclone separator that is arranged upstream of a main filter of the multi-stage fluid filter.

A combustion air filtration apparatus for filtering combustion air for an engine is disclosed. The combustion air filtration apparatus comprises a combustion air source and a filter system fluidly coupled to the combustion air source and to the engine to receive combustion air from the combustion air source and to supply filtered combustion air for the engine. The filter system comprises a first combustion air filter, a second combustion air filter flow-parallel to the first combustion air filter, and a flow control system fluidly coupled to the first combustion air filter and the second combustion air filter to direct flow of combustion air selectively between the first combustion air filter and the second combustion air filter.

One embodiment of the invention relates to an internal combustion engine including an engine block, a crankshaft configured to rotate about a crankshaft axis, a flywheel coupled to the crankshaft, a throttle body, an electric fan, and an air filter assembly configured to filter incoming air from an air intake and provide cleaned air to a throttle body. The engine block includes a cylinder. The throttle body is configured to throttle incoming air to the cylinder.