JP4685527B2 - Motorcycle exhaust system - Google Patents

Description

  The present invention relates to an improvement in an exhaust device for a motorcycle.

2. Description of the Related Art As a conventional motorcycle exhaust device, an exhaust device including an exhaust pipe and a muffler disposed behind an engine is known (for example, see Patent Document 1).
JP 2002-37174 A

  As shown in FIG. 4 of Patent Document 1, the exhaust device includes a first exhaust pipe 53 extending in a substantially S shape rearward from the lower part of the cylinder head 35 constituting the engine body 22, and a rear of the first exhaust pipe 53. The exhaust muffler 54 is connected to the end and extends in the vehicle width direction, and the second exhaust pipe 55 is connected to the end of the exhaust muffler 54.

  Steps 65 and 65 are attached to the lower part of the crankcase 36 of the engine body 22 via a step holder 64, and a side stand 67 is attached to the step holder 64 via a stand support member 66.

  The first exhaust pipe 53 has a portion in the vicinity of the attachment portion to the cylinder head 35 and a portion in the vicinity of the connection portion to the exhaust muffler 54 projecting in the vehicle width direction and exposed to the outside in plan view. The exhaust muffler 54 is connected to the second exhaust pipe 55. Since the end of the connecting portion protrudes in the vehicle width direction and is exposed to the outside in plan view, there is room for improvement in terms of appearance and protection of the exhaust pipe. Therefore, if a cover is provided on a portion exposed to the outside in consideration of appearance and protection of the exhaust pipe, the cost increases.

Further, when a catalyst is provided in the exhaust device for purifying exhaust gas, it is desirable to arrange the catalyst using the narrow space around the engine body 22 effectively.
Furthermore, even when water enters the exhaust muffler 54, an exhaust device that has little influence on the engine and that has high engine startability is desired.

  The object of the present invention is to improve the appearance and the protection of the exhaust pipe while suppressing the cost increase by improving the exhaust system of the motorcycle, and also effectively disposing the catalyst in the dead space. It is to improve the engine startability even when it is flooded.

According to the first aspect of the present invention, the main frame is extended rearward and obliquely downward from the head pipe, a power unit is attached to the lower portion of the main frame, a pivot plate is provided at the rear of the main frame, and a rear fork is swingably mounted on the pivot plate. Attach and support the rear wheel with this rear fork, and in the motorcycle where the muffler is arranged behind the power unit , the power unit has a substantially horizontal cylinder, has a crankcase behind this cylinder, and is below the lower end of the cylinder. The crankcase bulges , a catalyst is provided in the middle of the exhaust pipe connecting the power unit and the muffler, the catalyst is provided in front of the crankcase of the power unit and provided along the front-rear direction of the cylinder of the power unit in plan view , and The catalyst is a cylinder and cylinder head. Characterized in that the disposed below.

  The catalyst is arranged in a space along the front-rear direction of the cylinder in front of the crankcase, so that the space is effectively used. Further, by disposing the catalyst along the front-rear direction of the cylinder, the exhaust pipe connected to the catalyst is also easily disposed in the front-rear direction, and hardly protrudes in the vehicle width direction.

The invention according to claim 2 is characterized in that the catalyst is overlapped with the cylinder in plan view.
The catalyst overlaps the cylinder in plan view, does not protrude in the vehicle width direction, and is difficult to be exposed to the outside.

The invention according to claim 3 is characterized in that the muffler is disposed between the power unit and the rear wheel.
By providing the muffler between the power unit and the rear wheel, the muffler can be arranged so as not to be exposed from the outside.

In the invention according to claim 4, the exhaust pipe is connected to the lower side of the cylinder head, bends forward and extends substantially horizontally forward, and bends backward in the vehicle width direction at the substantially horizontal portion, and thereafter It is characterized by being connected to the catalyst .

According to a fifth aspect of the present invention, the muffler is formed in an L-shape in a plan view including a wide front part for accommodating the end part of the exhaust pipe and a vertically long rear part for accommodating the separator and the communication pipe, and the open end of the exhaust pipe is formed. It is characterized by being arranged above the rear end of the tail pipe of the muffler.
When water enters the muffler from the tail pipe, water does not enter the engine side from the open end of the exhaust pipe.

The invention according to claim 6 is characterized in that an opening of the communication pipe is provided above the rear end of the tail pipe.
When water enters the muffler from the tail pipe, an air layer remains in the communication pipe, so that the exhaust resistance of the engine is reduced.

In the invention according to claim 1, the main frame is extended rearward and obliquely downward from the head pipe, the power unit is attached to the lower portion of the main frame, the pivot plate is provided at the rear portion of the main frame, and the rear fork is swingably mounted on the pivot plate. Attach and support the rear wheel with this rear fork, and in the motorcycle where the muffler is arranged behind the power unit, the power unit has a substantially horizontal cylinder, has a crankcase behind this cylinder, and is below the lower end of the cylinder. The crankcase bulges , a catalyst is provided in the middle of the exhaust pipe connecting the power unit and the muffler, the catalyst is provided in front of the crankcase of the power unit and provided along the front-rear direction of the cylinder of the power unit in plan view , and The catalyst is Since disposed below the de, can be utilized effectively dead space to and beneath the cylinder in front of the crankcase, it can be made compact. Further, since the exhaust pipe is disposed along the front-rear direction of the vehicle body and does not protrude in the vehicle width direction and is difficult to be exposed to the outside, the appearance can be improved and the exhaust pipe can be protected.
Further, since the cylinder is substantially horizontal, the catalyst can be disposed substantially horizontally below the cylinder.

  In the invention according to claim 2, since the catalyst is overlapped with the cylinder in a plan view, the catalyst does not protrude in the vehicle width direction and can hardly be exposed to the outside, and the appearance can be improved.

  In the invention according to claim 3, since the muffler is disposed between the power unit and the rear wheel, the muffler can be disposed so as not to be exposed from the outside, and the appearance can be improved.

In the invention according to claim 4, the exhaust pipe is connected to the lower side of the cylinder head, bends forward and extends substantially horizontally forward, and bends backward in the vehicle width direction at the substantially horizontal portion, and thereafter Was connected to the catalyst.

  In the invention according to claim 5, the muffler is formed in an L-shape in a plan view including a wide front part for accommodating the end part of the exhaust pipe and a vertically long rear part for accommodating the separator and the communication pipe, and the open end of the exhaust pipe is formed. Since it is arranged above the rear end of the tail pipe of the muffler, even if water enters the muffler from the tail pipe, water can hardly enter the engine side from the open end of the exhaust pipe. Startability can be improved.

  In the invention according to claim 6, since the opening portion of the communication pipe is provided above the rear end of the tail pipe, the engine startability can be improved even when water enters the muffler from the tail pipe. .

The best mode for carrying out the present invention will be described below with reference to the accompanying drawings. The drawings are viewed in the direction of the reference numerals.
FIG. 1 is a side view of a motorcycle equipped with an exhaust device according to the present invention. A motorcycle 10 includes a main frame 12 extending rearward and obliquely downward from a head pipe 11 and a rear end of the main frame 12. A pair of left and right pivot plates 13 and 14 (only the reference numeral 13 on the front side) mounted so as to extend downward in the section supports a power unit 18 including an engine 16 and a transmission 17, and rearward from the rear portion of the main frame 12. A fuel tank 23 is attached to a pair of left and right rear frames 21 and 22 (only the reference numeral 21 shown on the front side) extending obliquely upward, and a storage box 24 is attached to the fuel tank 23 and the rear frames 21 and 22, This is a vehicle in which a tandem seat 26 is attached to a box 24 so as to be freely opened and closed.

The head pipe 11 is a member on which a front fork 31 that supports the front wheel 28 at the lower end is attached so as to be steerable, and supports the bar handle 32 at the upper part of the front fork 31.
The pivot plates 13 and 14 and the rear frames 21 and 22 span a pair of left and right subframes 34 and 34 (only the reference numeral 34 is shown on the front side), and a pair of left and right pillion steps 36 and 37 for passengers. A pair of left and right step support frames 41 and 42 that respectively support (only the front side reference numeral 36 is shown) are attached.

The head pipe 11, the main frame 12, the pivot plates 13 and 14, the rear frames 21 and 22, and the sub frames 34 and 34 are members constituting the vehicle body frame 45.
The pivot plates 13 and 14 are members to which a swing arm 47 that supports the rear wheel 46 at the rear end is swingably attached.

The engine 16 is provided with a substantially horizontal cylinder portion 50 at the front, and an intake device 52 and an exhaust device 53 are connected to a cylinder head 51 provided in the cylinder portion 50.
The intake device 52 includes an air cleaner 55 attached to the front portion of the main frame 12, and an injector integrated throttle body 57 having one end connected to the air cleaner 55 and the other end connected to the cylinder head 51 via an intake pipe 56. Prepare.

The exhaust device 53 includes an exhaust pipe 61 having one end connected to the cylinder head 51, a catalyst 62 provided in the middle of the exhaust pipe 61, and a muffler 63 connected to the rear end of the exhaust pipe 51. It is arranged behind the power unit 18.
The catalyst 62 has a higher ground clearance by being disposed in a space 64 formed below the cylinder portion 50 and in front of a crankcase 65 described later.

  The power unit 18 includes a crankcase 65, is attached to a lower portion of the crankcase 65, and has main steps 66 and 66 (only the reference numeral 66 on the near side is shown) for a driver extending on both sides. A rear wheel brake pedal 67 and a main stand 68 are swingably supported at the lower rear end of the crankcase 65.

  Here, 71 is a handle cover, 72 is a front cover, 73 is a battery disposed in front of the head pipe 11, 73a is a battery support bracket attached to the front of the head pipe 11 to support the battery 73, and 74 is a front wheel. Front fender covering the upper and rear of 28, 76 is a leg shield, 77 is opened and closed when fueling from a fuel filler port 23e (see FIG. 3, 78 is a cap for closing the fuel filler port) provided in the fuel tank 23. An oiling lid with a locking device provided on the leg shield 76, 81 an engine hanger attached to the main frame 12, 82 a drum brake device attached to the rear wheel axle 83, and 84 for preventing the drum brake device 82 from rotating. To the brake panel (not shown) of the drum brake device 82 and the swing arm 47. Crode 86 is a rear cushion unit 47 which is provided on the rear cushion bracket 47a and one rear frame 21 provided on the swing arm 47, 87 is a mudguard attached to the lower rear portion of the storage box 24, and 88 is located above the rear wheel 46. A rear fender for covering, 91 is a grab rail, and 92 is a tail lamp.

  FIG. 2 is a plan view of an essential part of the motorcycle according to the present invention (the arrow (FRONT in the figure indicates the front of the vehicle; the same applies hereinafter)), and the exhaust pipe 61 extends downward and rearward from the cylinder head 51 of the engine 16. A muffler 63 is connected to the rear end of the exhaust pipe 61 in the vicinity of the rear end of the crankcase 65 of the power unit 18, and a pair of left and right stands integrally with the rear end of the crankcase 65. Support bosses 65S and 65S are provided, shaft support holes 65a and 65b are opened in the stand support bosses 65S and 65S, respectively, and the support shaft 101 is passed through the shaft support holes 65a and 65b. It shows that the main stand 68 is swingably supported.

  The exhaust pipe 61 extends substantially linearly below the power unit 18 in the vehicle front-rear direction, and the catalyst 62 extends in the vehicle front-rear direction and substantially overlaps the cylinder portion 50 of the engine 16 in plan view. It is located in front of the vehicle relative to the portion 65c and the right bulge portion 65d.

  The muffler 63 has an L-shape comprising a wide front portion 63a disposed between the power unit 18 and the rear wheel 46, and a vertically long rear portion 63b extending rearward from the wide front portion 63a along the right side surface of the rear wheel 46. It is of shape.

The wide front part 63a is provided with a left part attaching part 63c attached to one pivot plate 13 (see FIG. 1), and the vertically long rear part 63b is provided with a right part attaching part 63d attached to one step support frame 42.
The torque rod 84 has a front end attached to a cross member 105 that connects the left and right arm portions 103 and 104 of the swing arm 47.

Here, 111 is a mounting bracket for attaching the leg shield 76 to the cylinder portion 50, 112 is a change pedal provided in the transmission 17, 113 is a side stand, and 114 is a pivot plate 13, 14 for supporting the swing arm 47 (see FIG. 1). ), A pivot shaft 116 for starting the engine, and a step bar 117 for attaching the left and right main steps 66, 66 to the crankcase 65 side.
The pivot shaft 114 described above supports the left and right step support frames 41 and 42 together with the swing arm 47.

  FIG. 3 is a side view of the main part of the motorcycle according to the present invention. The fuel tank 23 has bolts 123 and nuts attached to tank mounting brackets 121 and 122 having flange portions 23a attached to the left and right rear frames 21 and 22, respectively. 124 (the nut 124 is fixed to the lower surface of the tank mounting brackets 121 and 122). A fuel pump 125 is disposed in the fuel tank 23 and attached to the upper wall of the fuel tank 23.

  The tank mounting brackets 121 and 122 are members attached before and after the bent portions 21b and 22b (only the front side 21b is shown) of the rear frames 21 and 22, and the fuel tank 23 includes the bent portions 21b and 22b. Therefore, the fuel tank 23 can serve as a reinforcing material for the rear frames 21 and 22, and the rigidity of the rear frames 21 and 22 can be improved. Further, since the fuel tank 23 is provided to the left and right rear frames 21 and 22, and also serves as a cross member of the vehicle body frame 45, it can greatly contribute to the improvement of the overall rigidity of the vehicle body frame 45.

  The rear end portion 12a of the main frame 12 is a portion that is reduced to a height H2 with respect to the height H1 on the front side by crushing up and down, thereby lowering the position of the bottom surface 23f of the fuel tank 23, The capacity of the fuel tank 23 was expanded.

  The storage box 24 has a pair of left and right front lower protrusions 24a and 24a (only the front side reference 24a is shown) and a pair of left and right rear lower protrusions 24b and 24b (only the front side 24b is shown) on the bottom. The front lower protrusions 24a and 24a are attached to a pair of left and right box mounting brackets 126 and 126 (only the reference numeral 126 on the front side) attached to the upper surface of the fuel tank 23 with a bolt 128 and a nut member 131, and the rear part. The downward projecting portions 24b and 24b are attached to box mounting brackets 127 attached to the rear frames 21 and 22 with bolts 128 and nut members 131, respectively.

  The nut member 131 is a cylindrical member having a flange at one end. The nut member 131 is provided with a female screw on the inner surface of the cylinder. The nut member 131 is passed through the insertion holes formed in the box mounting brackets 126 and 127 from the bottom to the box mounting brackets 126 and 127. It is fixed by welding.

  The storage box 24 is attached to the box mounting brackets 126 and 127 at the portions of the nut member 131 that protrude upward from the box mounting brackets 126 and 127, at the front lower protrusions 24 a and 24 a and the rear lower protrusions of the storage box 24. Positioning is performed by fitting through holes opened in 24 b and 24 b and screwing the bolts 128 into the female screws of the nut member 131 from within the storage box 24.

The muffler 63 is a container having a lower muffler half 135 connected to the exhaust pipe 61 and an upper muffler half 136 aligned vertically.
The lower muffler half body 135 includes a lower bulging portion 135a that bulges downward to a position where the bottom surface of the lower muffler half body 135 overlaps the main stand 68 in a state of being flipped up.

  The left mounting portion 63c, which is the mounting portion of the muffler 63 to the pivot plate 13, includes a mounting bracket 137 that is mounted across the lower muffler half 135 and the upper muffler half 136, and nuts that are mounted on the side surfaces of the mounting bracket 137 (not shown). The bolt 138 is passed through a bolt insertion hole (not shown) opened in the lower end portion of one pivot plate 13 and screwed into the nut (not shown), whereby the left mounting portion is attached to the pivot plate 13. Install 63c.

  A right attachment portion 63d, which is an attachment portion of the muffler 63 to the step support frame 42 (the frame on the back side of the step support frame 41), is an attachment bracket 141 attached to the upper muffler half 136, and the attachment bracket 141. The right side mounting portion 63d is attached to the step support frame 42 by attaching the cylindrical member 142 to the bracket 144 provided on one step support frame 42 with a bolt 146 and a nut 147. .

  The step support frames 41 and 42 are respectively attached at lower portions to pivot plates 13 and 14 (the pivot plate 14 is not shown) coaxially with the swing arm 47 by bolts 151 and upper portions are brackets 152 and 42 provided on the rear frames 13 and 14, respectively. 152 (only the reference numeral 152 on the near side is shown) is attached with a bolt 153.

  FIG. 4 is a rear view of the main part of the motorcycle according to the present invention. The main stand 68 and the brake pedal 67 are attached to the stand support bosses 65S and 65S provided at the rear end of the power unit 18 via the support shaft 101. Indicates. The main stand 68 is in a standing state. Reference numeral 155 denotes the ground.

  The main stand 68 includes plate members 165 and 166 supported by the support shaft 101 so as to be swingable, arm members 167 and 168 made of pipes attached to the plate members 165 and 166, and arm members 167 and 168, respectively. A cross member 171 that is handed over, a side protrusion member 172 that protrudes outward from the lower portion of one arm member 167 to allow the driver to step on and swing the main stand 68, and a side protrusion member 172 And a reinforcing member 173 attached to the arm member 167 from the base portion. Reference numeral 175 denotes a pin attached to one plate member 165, and a main stand 68 erected by extending a tension coil spring 178 between the pin 175 and the pin 177 on the bracket 176 side attached to the crankcase 65. Can be lifted up to the storage position by the tensile force of the tension coil spring 178.

  The brake pedal 67 includes a cylindrical member 181 that is rotatably attached to the support shaft 101, an arm member 182 that is attached to the cylindrical member 181, and a pedal portion 183 that is attached to the tip of the arm member 182 so that the driver can put his / her foot on it. And a small arm member 184 attached to the cylindrical member 181 for connection to the drum brake device 82 (see FIG. 1) side on the rear wheel side.

  The support shaft 101 has a disc-shaped head portion 101a at one end, and sequentially passes through the cylinder member 181 of the brake pedal 67, the spacer 185, the plate member 166, the shaft support hole 65b, the shaft support hole 65a, and the plate member 165. After that, the detachment pin 186 is attached to the other end portion to prevent it from coming off.

  The exhaust pipe 61 is located in a space 188 surrounded by the support shaft 101, the arm members 167 and 168, and the cross member 171, and is located on the inner side in the vehicle width direction of the plate members 165 and 166 from the plate member 165 and the plate member 166, respectively. Pass between. That is, the exhaust pipe 61 passes between the left and right arm members 167 and 168 when the main stand 68 stands.

FIG. 5 is a side view (partially sectional view) of the muffler according to the present invention, and shows a state where the upper muffler half 136 (see FIG. 3) is removed.
The muffler 63 houses the rear end portion 61a of the exhaust pipe 61 in the wide front portion 63a, and attaches the first separator 195 and the second separator 196 disposed rearwardly of the first separator 195 to the vertically long rear portion 63b. The first separator 195 and the second separator 196 are attached so as to pass through the two first communication pipes 197 and 197, and the second separator 196 is made shorter than the first communication pipes 197 and 197. The second communication pipes 198 and 198 and the tail pipe 201 are attached so as to pass through, respectively, and the rear end of the tail pipe 201 is attached so as to penetrate the rear wall 63f of the vertically long rear part 63b.

  FIG. 6 is a plan view of the muffler according to the present invention, showing a state where the upper muffler half 136 (see FIG. 3) is removed, and the inside of the muffler 63 is partitioned by a first separator 195 and a second separator 196. The first chamber 211, the second chamber 212, and the third chamber 213, which are expansion chambers, are formed, and the rear end portion 61a of the exhaust pipe 61 is disposed in the first chamber 211.

  The rear end portion 61a of the exhaust pipe 61 is inserted from the outside of the muffler 63 into the exhaust pipe main body end portion 61c bent at a substantially right angle, and is connected to the exhaust pipe main body end portion 61c via a joint pipe 61d. The extension pipe 61e is extended from the exhaust pipe main body end portion 61c by changing its direction by approximately 180 °, and the end pipe 61f is connected to the tip of the extension pipe 61e and has a plurality of exhaust holes. Is a portion supported by a bracket 215 provided on the lower muffler half 135.

  The first communication pipes 197 and 197 communicate the first chamber 211 and the third chamber 213, the second communication pipes 198 and 198 communicate the second chamber 212 and the third chamber 213, and the tail pipe 201 The second chamber 212 communicates with the outside.

  Accordingly, the exhaust gas flowing from the engine side into the first chamber 211 through the exhaust pipe 61 flows into the third chamber 213 through the first communication pipes 197 and 197 and passes through the second communication pipes 198 and 198 from the third chamber 213. Through the second chamber 212, expand and mute, and are discharged from the second chamber 212 to the outside through the tail pipe 201.

FIG. 7 is a cross-sectional view taken along line 7-7 of FIG. 5, in which the first communication pipes 197, 197 and the second communication pipes 198, 198 are arranged vertically, respectively, and these first communication pipes 197, 197 and second It shows that the tail pipe 201 is disposed between the communication pipes 198 and 198.
Of the first communication pipes 197 and 197 and the second communication pipes 198 and 198, one first communication pipe 197 is located at the uppermost position.

  Returning to FIG. 5, when the horizontal line 220 passing through the opening 201a at the rear end of the tail pipe 201, specifically, the upper end 201b of the opening 201a (the upper end 201b is represented by a dot), the exhaust pipe 61 The rear end opening 61h of the extension pipe 61e (that is, the open end of the exhaust pipe 61) is disposed above the horizontal line 220, and one first communication pipe 197 is disposed above the horizontal line 220. It shows that the front opening 197 a and the rear opening 197 b of the first communication pipe 197 are arranged above the horizontal line 220.

  For example, even when water enters the muffler 63 from the opening 201a of the tail pipe 201, the opening 61h of the extension pipe 61e is at a position higher than the horizontal line 220, so that water flows from the extension pipe 61e to the engine side of the exhaust pipe 61. Since the first communication pipe 197 is located at a position higher than the horizontal line 220 without entering the engine, the air resistance in the first communication pipe 197 does not increase the exhaust resistance of the engine. There is no waking and engine starting is not difficult.

  FIG. 8 is a bottom view of the muffler according to the present invention. When the main stand 68 is flipped up and stored on the bottom surface 135c of the lower muffler half 135 of the muffler 63, a concave shape is formed to prevent interference with the arm member 168. This shows that the escape portion 135d is formed. Thereby, the ground clearance of the main stand 68 can be increased while securing the capacity of the muffler 63.

  Further, by stacking the muffler 63 and the arm member 168 vertically, for example, in the present invention, in the vehicle width direction of the muffler 63 or the main stand 68, compared to arranging the muffler and the arm member of the main stand side by side. Can be reduced, the vehicle can be downsized and the appearance can be improved.

  The exhaust device of the present invention is suitable for a motorcycle.

1 is a side view of a motorcycle equipped with an exhaust device according to the present invention. 1 is a plan view of a main part of a motorcycle according to the present invention. 1 is a side view of a main part of a motorcycle according to the present invention. 1 is a rear view of a main part of a motorcycle according to the present invention. It is a side view of the muffler concerning the present invention. It is a top view of the muffler concerning the present invention. FIG. 7 is a cross-sectional view taken along line 7-7 in FIG. 5. It is a bottom view of the muffler concerning the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Motorcycle, 11 ... Head pipe, 12 ... Main frame, 13, 14 ... Pivot plate, 18 ... Power unit, 46 ... Rear wheel, 47 ... Rear fork (swing arm), 50 ... Cylinder (cylinder part), 61 ... Exhaust pipe, 61a ... exhaust pipe end (rear end), 61h ... exhaust pipe open end (opening), 62 ... catalyst, 63 ... muffler, 63a ... wide front, 63b ... vertically long rear, 65 ... crankcase , 195, 196 ... separators (first separator, second separator), 197, 198 ... communication pipe (first communication pipe, second communication pipe), 197a, 197b ... openings (front opening, rear opening), 201 ... tail pipe, 201a ... rear end (opening) of tail pipe.

Claims (6)

A main frame (12) is extended rearward and obliquely downward from the head pipe (11), a power unit (18) is attached to the lower portion of the main frame (12), and a pivot plate (13) is provided at the rear of the main frame (12). A rear fork (47) is swingably attached to the pivot plate (13), a rear wheel (46) is supported by the rear fork (47), and a muffler (63) is disposed behind the power unit (18) . In motorcycles,
The power unit (18) has a substantially horizontal cylinder (50), a crankcase (65) is provided behind the cylinder (50), and the crankcase (65) expands below the lower end of the cylinder (50). broth,
A catalyst (62) is provided in the middle of an exhaust pipe (61) connecting the power unit (18) and the muffler (63),
The catalyst (62) is provided in front of the crankcase (65) of the power unit (18) and is provided along the front-rear direction of the cylinder (50) of the power unit (18) in plan view, and the catalyst (62 ) Is disposed below the cylinder (50) and the cylinder head (51),
A motorcycle exhaust system characterized by the above. The exhaust system for a motorcycle according to claim 1, wherein the catalyst (62) overlaps the cylinder (50) in a plan view. The exhaust system for a motorcycle according to claim 1 or 2, wherein the muffler (63) is disposed between the power unit (18) and the rear wheel (46) . The exhaust pipe (61) is connected to the lower side of the cylinder head (51), bends forward and extends substantially horizontally forward, and bends rearward in the vehicle width direction at the substantially horizontal portion, and rearward thereof. The exhaust system for a motorcycle according to claim 1 , wherein the exhaust system is connected to the catalyst (62) . The muffler (63) is L-shaped in plan view comprising a wide front part (63a) for accommodating the end of the exhaust pipe (61) and a vertically long rear part (63b) for accommodating the separator (195) and the communication pipe (197). The exhaust pipe (61) is formed in a shape, and the open end (61h ) of the exhaust pipe (61) is disposed above the rear end (201a) of the tail pipe (201) of the muffler (63) . The exhaust device for a motorcycle according to any one of claims 4 to 6. The exhaust system for a motorcycle according to claim 5, wherein an opening (197a) of the communication pipe (197 ) is provided above a rear end (201a ) of the tail pipe (201) .

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