An exhaust device for guiding exhaust gas from an exhaust pipe in front of an engine to a muffler in a rear of the engine is provided. The exhaust device includes a catalyst case in which a catalyst configured to purify the exhaust gas that passes through the exhaust pipe is accommodated, and a chamber in which a muffling chamber configured to reduce an exhaust noise is formed downstream of the catalyst case. The catalyst case is disposed in a range from a front space with respect to the engine to a front part of a lower space of the engine. The chamber is disposed so as to occupy at least a rear part of the lower space of the engine.

A catalyst degradation determining device for a straddled vehicle that includes an engine, a catalyst for cleaning an exhaust gas from the engine, and a throttle valve that is controllable by cruise control of the straddled vehicle to keep a traveling speed of the straddled vehicle constant. The catalyst degradation determining device includes a determiner that determines whether the cruise control is being executed, and an execution controller. The execution controller is configured to determine a degradation state of the catalyst while controlling an air-fuel mixture supplied through the throttle valve to the engine, in a case where the determiner determines that the cruise control is not being executed, and at least one running state of the straddled vehicle satisfies at least one predetermined allowable condition, and not to determine the degradation state of the catalyst in a case where the determiner determines that the cruise control is being executed.

A catalyst deterioration determining device for use in a straddled vehicle having an engine, a transmission that transmits motive power of an engine, and a catalyst that cleans an exhaust gas from the engine. The catalyst deterioration determining device includes a running state acquirer that acquires a plurality of running states, a state determiner that stores a plurality of allowable conditions, each of which is a condition for determining work in regard to a degradation state of the catalyst to be executed and is based on a relationship among a plurality of gear ratios of the transmission, an intake state of the engine and a rotation speed of the engine, and determines whether the plurality of running states acquired by the running state acquirer satisfy the plurality of allowable conditions, and a determination executor that executes the determining work based on a result of the determination by the state determiner.

An exhaust gas system for an internal combustion engine of a single-track vehicle can be arranged on an exhaust gas outlet of a cylinder head. A first lambda probe close to the cylinder head is provided in the exhaust gas system and is arranged before an exhaust gas cleaning system in the flow direction of an exhaust gas. A second lambda probe is provided in the exhaust gas system after the exhaust gas cleaning system in the flow direction of the exhaust gas. The second lambda probe is arranged at a maximum distance away from the exhaust gas cleaning system equal to four times the diameter of the exhaust gas cleaning system. As a result of the design, the lambda probe is arranged in the non-visible region of the single-track vehicle, while simultaneously examining the quality of the exhaust gas cleaning.

A straddle-type vehicle (100) includes a frame (20) and an engine (10) mounted on the frame (20), the engine (10) includes a cylinder head (11) positioned toward the rear end of the frame, and located below a saddle seat (80). The cylinder head laces toward the rear end of the frame, which allows the heated cylinder head of the engine and the exhaust pipe connected to the cylinder head to avoid contact with the vehicle the user's legs while riding the vehicle, so the effect of heat emitted from the cylinder head on the rider's experience is reduced.

A straddle-type vehicle (100) includes a frame (20) and an engine (10) mounted on the frame (20). The engine (10) includes a cylinder head (11) positioned toward the rear end of the frame, and located below a saddle seat. The cylinder head faces toward the rear end of the frame, which allows the heated cylinder head of the engine and the exhaust pipe connected to the cylinder head to avoid the position where the user's legs contact the vehicle while riding, so the effect of heat emitted from the cylinder head on the rider's experience is reduced.

An exhaust device for an internal combustion engine of a saddled vehicle includes an exhaust muffler disposed on an outer side of a rear wheel so as to overlap the rear wheel when viewed from a side a muffler protector which covers the muffler. The muffler protector includes an inner protector half body covering the exhaust muffler from the rear wheel side and an outer protector half body covering the exhaust muffler from a vehicle outer side opposite to the rear wheel The inner protector half body is detachably mounted on the exhaust muffler or the outer protector half body while maintaining a state in which the outer protector half body is mounted on the exhaust muffler.

A straddle-type vehicle includes a driver seat on which a driver rides, a cylinder head of an engine arranged in a region in front of and below the driver seat, an exhaust pipe that is connected to an exhaust port formed on a front surface of the cylinder head and exhausts exhaust of the engine, and a control unit that is arranged in an engine front space formed in front of the cylinder head, above the exhaust pipe, and below an upper end surface of the engine and controls the straddle-type vehicle.

An exhaust device in which a muffler is disposed on a side of a straddle-type vehicle includes the muffler including a tail pipe configured to discharge exhaust gas and protruding rearward, a tail cover covering a periphery of the tail pipe behind the muffler, and a protector for heat shield interposed between the muffler and the tail cover. Inner sides of the tail cover and the protector in a vehicle width direction are configured to be fixed to each other by a fastening member. An elastic locking portion is formed on an outer side of one of the tail cover and the protector in the vehicle width direction, and a holding portion configured to hold the elastic locking portion is formed on an outer side of another of the tail cover and the protector in the vehicle width direction.

An exhaust device for guiding exhaust gas from an exhaust pipe in front of an engine to a muffler in a rear of the engine is provided. The exhaust device includes a catalyst case in which a catalyst configured to purify the exhaust gas that passes through the exhaust pipe is accommodated, and a chamber in which a muffling chamber configured to reduce an exhaust noise is formed downstream of the catalyst case. The catalyst case is disposed in a range from a front space with respect to the engine to a front part of a lower space of the engine. The chamber is disposed so as to occupy at least a rear part of the lower space of the engine.