Abstract: An intake noise reduction device includes an air cleaner, an intake funnel and a resonator, and is connected to an engine via a throttle body. The resonator is provided inside of the air cleaner. The resonator includes a chamber portion and a pipe portion. The pipe portion is formed to extend downward from the chamber portion, and has an opening end at a lower end. The intake funnel is provided at a lower end of the air cleaner. An opening end of the resonator is inserted into the intake funnel. A cross sectional area of an intake passage between the intake funnel and the pipe portion is set to not less than an opening area of an intake passage of the throttle body opened to a maximum throttle opening.

Abstract: An intake noise reduction device includes an air cleaner, an intake funnel and a resonator, and is connected to an engine via a throttle body. The resonator is provided inside of the air cleaner. The resonator includes a chamber portion and a pipe portion. The pipe portion is formed to extend downward from the chamber portion, and has an opening end at a lower end. The intake funnel is provided at a lower end of the air cleaner. An opening end of the resonator is inserted into the intake funnel. A cross sectional area of an intake passage between the intake funnel and the pipe portion is set to not less than an opening area of an intake passage of the throttle body opened to a maximum throttle opening.

Abstract: Air flowing through a secondary air inducting conduit of a motorcycle is effectively cooled to enhance combustion efficiency of exhaust gas in a catalyzer. A part of the secondary air inducting conduit is exposed to a space behind a front wheel and in front of an engine, and thus acts as a secondary air cooling conduit section for cooling down secondary air flowing through the secondary air inducting conduit.

Abstract: An exhaust system for a motorcycle is configured to enhance output while maintaining a necessary noise level. The exhaust system includes an exhaust pipe connected to an engine, and a silencer connected to the exhaust pipe. The silencer includes a hermetically sealed outer cylinder and an inner cylinder disposed within the outer cylinder so as to extend along an axis of the outer cylinder. The outer cylinder has a front end portion connected to the exhaust pipe and a rear end portion opened toward the atmosphere. The inner cylinder includes a reduced diameter portion with a diameter which becomes smaller in the downstream direction, a throttle portion with a constant diameter, the throttle portion being connected to the reduced diameter portion, and an enlarged diameter portion connected to the throttle portion with a diameter which becomes larger in the downstream direction.

Abstract: An air cleaner 10 includes an air cleaner case 3 having an inlet 1 for introducing air and an outlet 2 for ejecting air. An intake pipe 5 having an intake opening 4 opened upward or obliquely upward in the air cleaner case 3 is connected to the outlet 2. The air cleaner 10 includes a main air filter element 6a positioned above the intake opening 4 and an auxiliary air filter element 6b, which is separate from the main air filter element 6a, positioned above the intake opening 4 but below the main air filter element 6a. The main air filter element 6a is configured to be detachable from the air cleaner case 3 with the auxiliary air filter element 6b fixed in the air cleaner case 3.

Abstract: A motorcycle includes a body frame having right and left frame members 15R and 15L and an air cleaner 10 having an air cleaner case 3 and an air filter element 6. The air cleaner case 3 includes a lower section 3a, a part of which being positioned between the frame members 15R and 15L and an upper section 3b protruding upward from the lower section 3a above the frame members 15R and 15L and laterally extending outward. The upper section 3b is positioned above the frame members 15R and 15L and laterally outward of inner ends 15a of the right and left frame members 15R and 15L. The upper section 3b has a seal section 26. The air filter element 6 is supported and sealed by the seal section 26 so as to divide the inner space of the air cleaner case 3 into an upper space and a lower space.

Abstract: A fuel supply system has an air chamber that contains a fuel injector. At least one aperture is formed in a substantially lowermost portion of a lower surface of the air chamber. The aperture and the lower surface have a generally uninterrupted or smooth transition or interface.

Abstract: An exhaust system for a motorcycle is configured to enhance output while maintaining a necessary noise level. The exhaust system includes an exhaust pipe connected to an engine, and a silencer connected to the exhaust pipe. The silencer includes a hermetically sealed outer cylinder and an inner cylinder disposed within the outer cylinder so as to extend along an axis of the outer cylinder. The outer cylinder has a front end portion connected to the exhaust pipe and a rear end portion opened toward the atmosphere. The inner cylinder includes a reduced diameter portion with a diameter which becomes smaller in the downstream direction, a throttle portion with a constant diameter, the throttle portion being connected to the reduced diameter portion, and an enlarged diameter portion connected to the throttle portion with a diameter which becomes larger in the downstream direction.

Abstract: A motorcycle includes a body frame having right and left frame members 15R and 15L and an air cleaner 10 having an air cleaner case 3 and an air filter element 6. The air cleaner case 3 includes a lower section 3a, a part of which being positioned between the frame members 15R and 15L and an upper section 3b protruding upward from the lower section 3a above the frame members 15R and 15L and laterally extending outward. The upper section 3b is positioned above the frame members 15R and 15L and laterally outward of inner ends 15a of the right and left frame members 15R and 15L. The upper section 3b has a seal section 26. The air filter element 6 is supported and sealed by the seal section 26 so as to divide the inner space of the air cleaner case 3 into an upper space and a lower space.

Abstract: An air cleaner 10 includes an air cleaner case 3 having an inlet 1 for introducing air and an outlet 2 for ejecting air. An intake pipe 5 having an intake opening 4 opened upward or obliquely upward in the air cleaner case 3 is connected to the outlet 2. The air cleaner 10 includes a main air filter element 6a positioned above the intake opening 4 and an auxiliary air filter element 6b, which is separate from the main air filter element 6a, positioned above the intake opening 4 but below the main air filter element 6a. The main air filter element 6a is configured to be detachable from the air cleaner case 3 with the auxiliary air filter element 6b fixed in the air cleaner case 3.

Abstract: An engine can include an air cleaner in communication with intake ports of the engine, and a wind introduction duct for introducing a wind into a primary chamber of the air cleaner. The wind introduction duct can include a resonator for absorbing predetermined frequencies. The resonator can have a predetermined capacity and can have a communication port in communication with the inside of the introduction duct.

Abstract: Air flowing through a secondary air inducting conduit of a motorcycle is effectively cooled to enhance combustion efficiency of exhaust gas in a catalyzer. A part of the secondary air inducting conduit is exposed to a space behind a front wheel and in front of an engine, and thus acts as a secondary air cooling conduit section for cooling down secondary air flowing through the secondary air inducting conduit.

Abstract: A motorcycle can include an air cleaner in communication with intake ports of its engine, and a wind introduction duct for introducing a wind into a primary chamber of the air cleaner. The wind introduction duct can extend from an outside air introduction port located forwardly from the intake port, passing by the front and rear intake ports and extending to the primary chamber of the air cleaner.

Abstract: An air intake device for an engine has a cleaner element. A housing encloses the cleaner element. The housing communicates with the engine downstream of the cleaner element. The housing has an intake section disposed upstream of the cleaner element. The intake section defines an air passage that has a plurality of inlet openings through which ambient air is introduced into the air passage. The inlet openings communicate with each other upstream of the cleaner element. The cleaner element faces the air passage.

Abstract: A motorcycle can include an air cleaner in communication with intake ports of its engine, and a wind introduction duct for introducing a wind into a primary chamber of the air cleaner. The wind introduction duct can extend from an outside air introduction port located forwardly from the intake port, passing by the front and rear intake ports and extending to the primary chamber of the air cleaner.

Abstract: An engine can include an air cleaner in communication with intake ports of the engine, and a wind introduction duct for introducing a wind into a primary chamber of the air cleaner. The wind introduction duct can include a resonator for absorbing predetermined frequencies. The resonator can have a predetermined capacity and can have a communication port in communication with the inside of the introduction duct.

Abstract: A fuel supply system has an air chamber that contains a fuel injector. At least one aperture is formed in a substantially lowermost portion of a lower surface of the air chamber. The aperture and the lower surface have a generally uninterrupted or smooth transition or interface.

Abstract: An air intake device for an engine has a cleaner element. A housing encloses the cleaner element. The housing communicates with the engine downstream of the cleaner element. The housing has an intake section disposed upstream of the cleaner element. The intake section defines an air passage that has a plurality of inlet openings through which ambient air is introduced into the air passage. The inlet openings communicate with each other upstream of the cleaner element. The cleaner element faces the air passage.