WO2006120835A1

WO2006120835A1 - Motorcycle

Info

Publication number: WO2006120835A1
Application number: PCT/JP2006/307886
Authority: WO
Inventors: Masaaki Yamaguchi; Hideki Ikeda
Original assignee: Honda Motor Co., Ltd.
Priority date: 2005-05-11
Filing date: 2006-04-07
Publication date: 2006-11-16
Also published as: BRPI0608775A2; TWI357391B; BRPI0608775B1; KR20080006626A; KR100930322B1; MY149679A; TR200707662T2; GR1005740B; TW200642901A; GR20060100266A; AR055941A1

Abstract

Motorcycle (10) includes a power unit (18) mounted to the underside of a main frame (12) extending in a rearward and downward direction from a head pipe (11). Rear fork (47) is pivotably mounted to pivot plates (13) provided on a rear portion of the main frame, a rear wheel (46) is supported by the rear fork. Muffler (63) is positioned between the power unit and the rear wheel and mounted to a lower end portion of one of the pivot plates, and a main stand (68) is pivotably mounted to a lower portion of a vehicle body in front of the muffler.

Description

DESCRIPTION

MOTORCYCLE

Technical Field

The present invention relates to motorcycles and more particularly to an improvement in exhaust devices that include an exhaust pipe and muffler.

Background Art

One example of a motorcycle where an exhaust device including an exhaust pipe and muffler is disposed rearwardly of an engine is known from Japanese Patent LaidOpen Publication No. 2002-37174.

Exhaust device disclosed in the publication includes a first exhaust pipe extending, in a substantial S shape, rearwardly from a lower portion of a cylinder head constituting the body of the engine, an exhaust muffler connected to the rear end of the first exhaust pipe and extending in a width direction of the vehicle (i.e., vehicle width direction), and a second exhaust pipe connected to an end of the exhaust muffler.

A pair of left and right steps is fixed, via a step holder, to lower portions of a crankcase of the engine body, and a side stand is fixed to an end of the step holder via a stand support member.

Portions of the first exhaust pipe, located near its connections to the cylinder head and to the exhaust muffler, protrude outwardly in the vehicle width direction and are exposed to the outside as viewed in plan. Further, an end portion of the exhaust muffler, connecting with the second exhaust pipe, protrudes outwardly in the vehicle width direction and is exposed to the outside as viewed in plan. Thus, with the disclosed conventional exhaust device, there is a room for further improvements in terms of the appearance and protection of the exhaust pipes. If the externally exposed portions are covered with some covering for a better appearance and effective protection of the exhaust pipes, a considerable extra cost is required.

Further, if the aforementioned motorcycle is to be provided with a main stand, in addition to the side stand, in order to improve the usability, it would be difficult to mount the main stand to a rear portion of the engine body or to the step holder because the first exhaust pipe and exhaust muffler are disposed near the engine body or step holder. Also, it is not preferable to mount the main stand to a bottom portion of the crankcase in front of the step holder in that the bottom portion of the crankcase is close to the front end of the vehicle body and the mounting, to the bottom portion, of the main stand would result in a loss of weight balance in a front-rear direction of the vehicle body.

Further, if a catalytic converter is to be provided in the exhaust device for purification of the exhaust, it is desirable that the exhaust device be positioned making efficient use of a small space around the body of the engine.

It is also desirable that the exhaust device be arranged such that, even when water has entered the exhaust muffler, the exhaust device can be activated with a high reliability while minimizing adversely influences on the engine. Disclosure of the Invention

According to the present invention, there is provided an improved motorcycle, which comprises- a head pipe; a main frame extending in a rearward and downward direction from the head pipe; a power unit mounted to the underside of the main frame; pivot plates provided on a rear portion of the main frame; a rear fork pivotably mounted to the pivot plates; a rear wheel supported by the rear fork; a muffler disposed between the power unit and the rear wheel and mounted to a lower end portion of one of the pivot plates; and a main stand pivotably mounted to a lower portion of a vehicle body in front of the muffler.

With the muffler provided between the engine and the rear wheel, the muffler can be prevented from being substantively exposed to the outside, and thus, it is possible to significantly improve the appearance of the motorcycle.

Also, an area beneath the pivot plates can be used as a mounting space for the muffler, and thus, the muffler can have an increased capacity.

Preferably, the power unit and the muffler are interconnected via an exhaust pipe, and the exhaust pipe is passed through a region located between left and right upper supported portions of the main stand. Thus, the exhaust device and muffler can be prevented from being substantively exposed to the outside, and thus, it is possible to significantly improve the appearance of the motorcycle. Further, because the main stand is mounted to a lower portion of the vehicle body over and across the exhaust pipe, it can be readily mounted without an interference between the main stand and the exhaust pipe.

Preferably, the main stand is supported by a portion of the power unit located below lower ends of the pivot plates. Thus, an area beneath the pivot plates can be used as a mounting space for the muffler, so that the muffler can have an increased capacity. Preferably, the main stand is disposed so as to overlap with the muffler as viewed in plan. Thus, the present invention can reduce the projecting amount, in the vehicle width direction, of the muffler or main stand as compared to a case where the arm member of the main stand is placed in generally-horizontal side-byside relation to the muffler, as a result of which it can reduce the overall size of the vehicle and improve the appearance of the vehicle.

Preferably, the muffler has a concavelyrecessed portion formed in the underside thereof for preventing an interference between the muffler and the main stand. By the provision of the concavely-recessed portion, it is possible to substantively increase the height, from the ground surface, of the main stand while securing a sufficient capacity of the muffler.

According to another aspect of the present invention, there is provided an improved motorcycle, which comprises '■ a head pipe; a main frame extending in a rearward and downward direction from the head pipe; a power unit mounted to an underside of the main frame; pivot plates provided on a rear portion of the main frame; a rear fork pivotably mounted to the pivot plates; a rear wheel supported by the rear fork; and a muffler disposed between the power unit and the rear wheel. The muffler has an L shape, as viewed in plan, which comprises a wide front section having received therein an end portion of an exhaust pipe connected to the power unit and a longitudinally-elongated rear section having received therein a separator and communicating pipe, the separator partitioning an interior of the muffler to form a plurality of expansion chambers, the expansion chambers communicating with each other via the communicating pipe. The exhaust pipe has an end opening located above a rear end of a tail pipe of the muffler.

Thus, even when water has entered the muffler through the tail pipe, the water can be effectively prevented from entering the engine via the end opening of the exhaust pipe. As a result, the engine can always be activated with a high reliability.

Preferably, in the present invention, the communicating pipe has openings located above the rear end of the tail pipe.

According to still another aspect of the present invention, there is provided an improved motorcycle, which comprises: a head pipe; a main frame extending in a rearward and downward direction from the head pipe; a power unit mounted to an underside of the main frame; pivot plates provided on a rear portion of the main frame; a rear fork pivotably mounted to the pivot plates; a rear wheel supported by the rear fork; a muffler disposed rearwardly of the power unit; an exhaust pipe connecting the power unit and the muffler; and a catalytic converter provided in an intermediate portion of the exhaust pipe in front of a crankcase of the power unit. The catalytic converter extends along a front-rear direction of a cylinder of the power unit as viewed in plan.

In the invention arranged in the above-described manner, a dead space formed in front of the crankcase and under the cylinder can be used efficiently, which can reduce the overall size of the motorcycle. Because the exhaust pipe is disposed along the front-rear direction of the vehicle body without projecting in the vehicle width direction and hence without being substantively exposed to the outside, the present invention can significantly improve the appearance and effectively protect the exhaust pipe.

The catalytic converter is disposed in overlapping relation to the cylinder as viewed in plan. Thus, the catalytic converter does not project in the vehicle width direction and hence is not substantively exposed to the outside, as a result of which the present invention can significantly improve the appearance. Preferably, the muffler is disposed between the power unit and the rear wheel. Thus, the muffler can be prevented from being substantively exposed to the outside, and thus, it is possible to significantly improve the appearance of the motorcycle.

Preferably, the cylinder extends substantially in a horizontal direction. Thus, the catalytic converter can be disposed substantially in the horizontal direction beneath the cylinder. Brief Description of Drawings

Fig. 1 is a side view of a motorcycle with an exhaust device in accordance with an embodiment of the present invention; Fig. 2 is a plan view showing in enlarged scale a power unit and exhaust device of Fig. 1 and other components around the power unit and exhaust device;

Fig. 3 is a side view showing a fuel tank, pivot plate and muffler of Fig. 1 and other components around the fuel tank, pivot plate and muffler;

Fig. 4 is an enlarged rear view of the motorcycle, which particularly shows a crankcase and other components around the crankcase;

Fig. 5 is a side view showing the exhaust device and muffler of Fig. 3 in enlarged scale; Fig. 6 is a plan view of the exhaust device and muffler;

Fig. 7 is a sectional view taken along the 7 — 7 lines of Fig. 5; and Fig. 8 is a bottom view of the muffler of Fig. 5.

Best Mode for Carrying Out the Invention

Fig. 1 is a side view of a motorcycle (i.e., two-wheeled motor vehicle) in accordance with an embodiment of the present invention. The motorcycle 10 is a vehicle, where as shown in Fig. 1, a power unit 18 comprising an engine 16 and transmission 17 is supported by a single main frame 12 extending in a rearward and downward direction from a head pipe 11 and a pair of left and right pivot plates 13 (only one of them 13 is shown in the figure) mounted to and extending downward from a rear end portion of the main frame 12. Fuel tank 23 is mounted to a pair of left and right rear frames 21 and 23 (only one of them 21 is shown in the figure) extending in a rearward and upward direction from a rear portion of the main frame 12, a storage box 24 is mounted on the fuel tank 23 and rear frames 21 and 22, and a tandem seat 26 is mounted on the storage box 24 for pivotal movement relative to the box 24 to close and open the box 24.

Front fork 31 having a front wheel 28 supported at its lower end portions is steerably fixed to the head pipe 11, and a bar handle 32 is supported on an upper end portion of the head pipe 11.

A pair of left and right sub-frames 34 (only one of which is shown in the figure) connect between the pivot plates 13 and the rear framed 21 and 22, and a pair of left and right pillion steps 36 and 37 (only one of them 36 is shown in the figure) for a pillion passenger are supported on a pair of step support frames 41 and 42.

The above-mentioned head pipe 11, main frame 12, pivot plates 13, rear frames 21 and 22 and sub-frames 34 together constitute a vehicle body frame- work 45.

Swing arm (i.e., rear fork) 47, supporting a rear wheel 46 at its rear end, is pivotably connected to each of the pivot plates 13.

The engine 16 includes in its front portion a cylinder section 50 extending substantially horizontally, and an intake device 52 and exhaust device 53 are connected to a cylinder head 51 of the cylinder section 50.

The intake device 52 includes an air cleaner 55 mounted to a front portion of the main frame 12, and an injector-equipped throttle body 57 connected at one end to the air cleaner 55 and connected at the other end to the cylinder heads 51 via an intake pipe 56. The exhaust device 53 includes an exhaust pipe 61 connected at one end to the cylinder head 51, a catalytic converter 62 provided in an intermediate portion of the exhaust pipe 62, and a muffler 63 connected to a rear end portion of the exhaust pipe 51. The muffler 63 is located rearwardly of the power unit 18. The catalytic converter 62 is disposed in a space 64 formed beneath the cylinder section 50 and in front of a later- described crankcase 65.

The power unit 18 includes the crankcase 65, and main steps 66 (only one of which is shown in the figure) for a driver are fixed to a lower portion of the crankcase 65 and extend laterally outward from the crankcase 65. Further, a rear-wheel brake pedal 67 and main stand 68 are pivotably fixed to a lower rear end portion of the crankcase 65. Reference numeral 71 indicates a handle cover, 72 a front cover, 73 a battery disposed in front of the head pipe 11, 73a a battery support bracket fixed to a front portion of the head pipe 11 for supporting the battery 73, 74 a front fender covering upper and rear portions of the front wheel 28, and 76 a leg shield (i.e., vehicle body cover). Further, reference numeral 77 indicates a fill lid equipped with a lock device and provided on the leg shield or vehicle body cover 76 for being opened and closed when fuel is fed through a fill opening 23e of the fuel tank 23 (see Fig. 3), and 78 indicates a cap for closing the fill opening 23e). Further, 81 indicates an engine hanger fixed to the main frame 12, 82 a drum brake device mounted on a rear wheel axle 83, 84 indicates a torque rod connecting between a brake panel (not shown) of the drum brake device 82 and the swing arm 47 for preventing rotation of the drum brake device 82, and 86 a rear cushion unit provided between a rear cushion bracket 47a fixed to the swing arm 47 and one of the rear frames 21. Furthermore, reference numeral 87 indicates a mud shield mounted to a lower rear portion of the storage box 24, 88 a rear fender covering an upper portion of the rear wheel 46, 91 a grab rail, and 92 a tail lamp.

Fig. 2 is an enlarged plan view showing the power unit and muffler of Fig. 1 and other components around the power unit. The exhaust pipe 61 extends downward from the cylinder head 51 of the engine 16 and then rearward along a lower surface of the power unit 18. The muffler 63 is connected to the rear end of the exhaust pipe 61 near a rear end portion of the crankcase 65 of the power unit 18. The crankcase 65 has a pair of left and right stand supporting bosses 65S formed integrally with a rear end portion the body of the crankcase

65, and shaft supporting holes 65a and 65b are formed in the left and right stand supporting bosses 65S, respectively. Support shaft 101 is passed through the shaft supporting holes 65a and 65b, and the brake peal 67 and main stand 68 are pivotably supported on the support shaft 101. Arrow labeled "FRONT" in the figure represents a direction toward the front of the motorcycle 10.

The exhaust pipe 61 extends substantially straight in a front-rear direction of the vehicle beneath the power unit 18. The catalytic converter 62 extends in the front-rear direction of the vehicle and substantially overlap with the cylinder section 50 of the engine 16 as viewed in plan, and the catalytic converter 62 is located in front of left and right bulging portions 65c and 65d of the crankcase 65.

The muffler 63 is an Lrshaped muffler that has a wide front section 63a and a longitudinally elongate rear section 63b extending rearwardly from the wide front section 63a along a right side surface of the rear wheel 46.

The wide front section 63a has a left mounting portion 63c attached to one of the pivot plates 13 (see Fig. l), and the longitudinally elongate rear section 63b has a right mounting portion 63d attached to one of the step support frames 42.

The torque rod 84 is connected at its front end to a cross member 105 connecting left and right arm portions 103 and 104 of the swing arm 47.

Reference numeral 111 indicates a mounting bracket fixing the leg shield

76 to the cylinder section 50, 112 a change pedal provided on the transmission 17, 113 a side stand, and 114 a pivot shaft connected to the pivot plates 13 (see

Fig. l) for supporting the swing shaft 47. Further, reference numeral 116 indicates a kick pedal for activating the engine, and 117 a step bar attached to the crankcase 65 for interconnecting the left and right main steps 66.

The above-mentioned pivot shaft 114 supports the left and right step support frames 41 and 42 as well as the swing arm 47.

Fig. 3 is a side view showing the fuel tank of Fig. 1, other components around the fuel tank, pivot plates and other components around the muffler.

As shown, the fuel tank 23 is connected at its flange portion 23a to tank mounting brackets 121 and 122 by means of bolts 123 and nuts 124 that are in turn fixed to the left and right rear frames 21 and 22; the nut 124 is secured to the undersides of the tank mounting brackets 121 and 122. Reference numeral 125 represents a fuel pump disposed within the fuel tank 23 and fixed to an upper wall of the fuel tank 23.

The tank mounting brackets 121 and 122 are fixedly mounted to portions of the rear frames 21 and 22 located forwardly of V-shaped bent portions 21b and 22b of the frames and to portions of the rear frames 21 and 22 located rearwardly of the bent portions 21b and 22b. Because the fuel tank 23 is fixed to the rear frame portions before and behind the bent portions 21b and 21b, the fuel tank 23 can function as a reinforcing member for the rear frames 21 and

22 and thereby enhance the rigidity of the rear frames 21 and 22. Further, because the fuel tank 23 connects between the left and right rear frames 21 and 22, it can function as a cross member of the vehicle body framework 45 and thereby greatly contribute to enhancement of the overall rigidity of the vehicle body framework 45.

The main frame 12 has a rear end portion 12a having a downwardly- dented upper surface. Thus, the rear end portion 12a has a height H2 smaller than a height Hl of a front portion of the main frame 12, so that the fuel tank

23 can have its underside 23f positioned at a lower level. Thus, the fuel tank 23 can have an increased size and hence an increased overall capacity. The storage box 24 has, in its bottom section, a pair of left and right front downward projecting portions 24a (only one of which 24a is shown in the figure) and a pair of left and right rear downward projecting portions 24b (only one of which 24b is shown in the figure). The front downward projecting portions 24a are fixed, via bolts 128 and nut members 131, to a pair of left and right box mounting brackets 126 (only one of which 126 is shown in the figure) secured to the upper surface of the fuel tank 23, and the rear downward projecting portions 24b are fixed, via bolts 128 and nut members 131, to a pair of left and right box mounting brackets 127 secured to the rear frames 127. Each of the nut members 131 is a cylindrical member having a flange at rts one end and internally threaded in its inner surface, and it is passed through an insertion hole, formed in the box mounting bracket 126 or 127, from beneath and secured to the box mounting bracket 126 or 127 by welding.

The storage box 24 is fixed to the box mounting brackets 126 and 127 by first fitting through-holes, formed in the front downward projecting portions 24a and rear downward projecting portions 24b of the storage box 24, over upward protrusions of the box mounting brackets 126 and 127 to thereby appropriately position the storage box 24 relative to the mounting brackets 126 and 127, and then screwing the bolts 128 from within the storage box 24 into the female threads of the corresponding nut members 131.

The muffler 63 comprises a lower muffler half 135 connected to the exhaust 61 and an upper muffler half 136, and these lower and upper muffler halves 135 and 136 are vertically coupled with each other (along their side edges) into a container shape. As viewed sideways, the lower muffler half 135 has a lower bulging portion 135a formed so that its underside is located to overlap with the main stand 68 in a lifted position. The left mounting portion 63c, at which the muffler 63 is attached to the pivot plate 13, has a mounting bracket 137 extending along respective end surfaces of the lower and upper muffler halves 135 and 136 and a nut (not shown) mounted on a side surface of the mounting bracket 137. The left mounting portion 63c is attached to the pivot plate 13 by a bolt 138 being passed through a bolt insertion hole (not shown), formed in a lower end portion of the pivot plate 13, and screwed into the above-mentioned not-shown nut.

The right mounting portion 63d, at which the muffler 63 is attached to the step support frame 42 (that is behind the step support frame 41 in Fig. 3), has a mounting bracket 141 secured to the muffler half 136 and a cylinder member 142 mounted on an upper portion of the mounting bracket 141. The right mounting portion 63d is attached to the step support frame 42 by the cylinder member 142 being fixed to a mounting bracket 144 by means of a bolt 146 and nut 147. The step support frames 41 and 42 are secured at their lower portions to the pivot plates 13 (only one of them 13 is shown in the figure) by means of bolts 151 concentrically with the swing arm 47 and also secured at their upper portions to the brackets 152 (only one of which is shown in the figure), fixed to the rear frames 13, by means of bolts 153. Fig. 4 is an enlarged rear view of the motorcycle, which particularly shows the crankcase and other components around the crankcase. More particularly, Fig. 4 shows the main stand 68 and brake pedal 67 fixed, via the support shaft 101, to the stand supporting bosses 65S provided on a rear end portion of the power unit 18. In the illustrated example, the main stand 68 is in an operative ground-engaging; reference numeral 155 indicates the ground surface.

The main stand 68 includes plate members (i.e., left and right upper supported portions) 165 and 166 pivotably supported via the support shaft 101, arm members 167 and 168 in the form of two pipes fixed to the plate members 165 and 166, respectively, and a cross member 171 connecting between and secured to the arm members 167 and 168. The main stand 68 also includes a lateral projecting member 172 projecting laterally outward, from a lower end portion of one of the arm members 167, so as to allow the driver of the motorcycle to pivot the main stand 68 with one of his or her feet, and a reinforcing member 173 connecting between and fixed to a proximal end portion of the lateral projecting member 172 and the arm member 167. Reference numeral 175 indicates a pin provided on one of the plate members 165. Tension coil spring 178 connects between the pin 175 and a pin 177 provided on a bracket 176 secured to the crankcase 65, so that the main stand 68 can pivot from the operative ground-engaging position to the lifted or non-operative retracted position by the tension force of the coil spring 178. The brake pedal 167 includes a cylinder member 181 rotatably mounted on the support shaft 101, an arm member 182 connected to the cylinder member 181, a pedal portion 183 provided at the distal end of the arm member 182 for the driver to place the other foot thereon, and a small arm member 184 fixed to the cylinder member 181 in order to operatively connect to the drum brake device 82 (see Fig. l) for the rear wheel.

The support shaft 101 includes a disk-shaped head portion 101a provided at its one end and sequentially extends through the cylinder member 181 of the brake pedal 167, spacer 185, plate member 166, shaft supporting holes 65b and 65a and plate member 165 in the mentioned order. Split pin 186 is provided to prevent the support shaft 101 from slipping off the predetermined place.

The exhaust pipe 61 is disposed in a space 188 surrounded by the support shaft 101, arm members 167, 168 and cross member 171 and extends in the front-rear direction through a region located inwardly of the plate members

165 and 166 (i.e., along and between the inner surfaces of the plate members 165 and 166). Namely, when the main stand 68 is held in the operative ground- engaging position, the exhaust pipe 61 extends in the front-rear direction through a region between the inner surfaces of the left and right arm members 167 and 168.

Fig. 5 is a side view showing the muffler 63 of Fig. 3 in enlarged scale with the upper muffler half 136 taken away for clarity of illustration.

Rear end section 61a of the exhaust pipe 61 is received in the wide front section 63a of the muffler 63, a first separator 195 and second separator 196 spaced apart rearwardly from the first separator 195 are mounted to the longitudinally elongate rear section 63b, and two first communicating pipes 197 extend through the first and second separators 195 and 196. Further, two second communicating pipes 198, smaller in length than the first communi- eating pipes 197, and tail pipe 201 extend through the second separator 196, and the tail pipe 201 has a rear end portion extending through a rear wall 63f of the longitudinally elongate rear section 63b.

Fig. 6 is a plan view showing the muffler 63 of Fig. 3 with the upper muffler half 136 taken away. As seen in Fig. 6, the interior of the muffler 63 is partitioned by the first and second separators 195 and 196 to provide first, second and third chambers 211, 212 and 213 that are each an expansion chamber. The rear end section 61a of the exhaust pipe 61 is disposed in the first chamber 211.

The rear end section 61a of the exhaust pipe 61 includes a body end portion 61c extending from outside the muffler 63 into the muffler 63 and bent substantially at a right angle, an extended pipe 6 Ie connected via a joint pipe 6 Id to the body end portion 61c and bent so as to extend at about 180 degrees relative to the body end portion 61c, and an end pipe 6 If connected to the distal end of the extended pipe 6 Ie and having a plurality of exhaust holes. The extended pipe 6 Ie is supported by a bracket 215 provided on the lower muffler half 135. The first and third chambers 211 and 213 communicate with each other via the first communicating chambers 197, the second and third chambers 212 and 213 communicate with each other via the second communicating chambers 198, and the second chamber 212 communicates with the outside via the tail pipe 201. Exhaust having flown from the engine into the first chamber 211 through the exhaust pipe 61 flows, through the first communicating chambers 197, to the third chamber 213, from which it further flows, through the second communicating chambers 198, to the second chamber 212. In this way, exhaust expansion and sound deadening can be effected appropriately, and the exhaust is ultimately discharged to the outside via the tail pipe 201.

Fig. 7 is a view taken along the 7 — 7 lines of Fig. 5, which particularly shows a manner in which the first communicating chambers 197 and second communicating chambers 198 are arranged with the tail pipe 202 disposed therebetween. As shown, one of the first communicating chambers 197 is located at the highest level of all of the chambers 197 and 198.

As seen in Fig. 5, a rear end opening 6 Ih of the extension pipe 6 Ie of the exhaust pipe 61 (namely, open end of the exhaust pipe 6l) is located above a horizontal line 220 passing a rear end opening 201a of the tail pipe 201 (more particularly passing an upper end point 201b of the rear end opening 201a), and at least one of the communicating chambers 197 is also located above the horizontal line 220. Thus, front and rear openings 197a and 197b of the first communicating chamber 197 are located above the horizontal line 220. For example, even when water has entered the muffler 63 through the opening 201a of the tail pipe 201, the water can be effectively prevented from entering, through the extension pipe 6 Ie, a portion of the discharge pipe 61 adjacent to the engine because the rear end opening 6 Ih of the extension pipe 6 Ie is located above the horizontal hue 220. Further, because the first communicating chamber 197 is also located above the horizontal line 220, exhaust resistance in the engine can be prevented from increasing due to layers of air; thus, it is possible to avoid an engine failure during operation of the engine and a difficulty encountered in activating the engine. Fig. 8 is a bottom view of the muffler of Fig. 5, which particularly shows a clearance portion 135d, in the form of a concavely recessed portion, formed in an underside 135c of the lower muffler half 135 for preventing interference between the underside 135c of the lower muffler hah⁰ 135 and the arm member 168 of the main stand 68 when the main stand is lifted to the non-operative retracted position. With the clearance portion 135d thus provided, it is possible to substantively increase the height, from the ground surface, of the main stand 68 while securing a sufficient capacity of the muffler 63.

Further, with the arm member 168 positioned under the underside of the muffler 63, the instant embodiment of the present invention can reduce the projecting amount, in the vehicle width direction, of the muffler 63 or main stand 68 as compared to a case where the arm member of the main stand is placed in generally-horizontal side-by-side relation to the muffler, as a result of which it can reduce the overall size of the vehicle and improve the appearance of the vehicle. Whereas the muffler 63 has been described as supported by the bracket

144 provided on the step support frame 42 supporting the pivot plate 13 and pillion step 37, it may be supported by the left and right step support frames 41 and 42 that support the left and right pillion steps 36 and 37.

Further, whereas the main stand 68 has been described as supported by the engine, it may be supported by the pivot plate 13; in this case too, the exhaust pipe 61 is disposed to extend through a region located inwardly of the plate members (upper supported portions) 165 and 166 of the main stand 68.

Industrial Applicability

The present invention is particularly useful when applied to motorcycles including a muffler and brake pedal.

Claims

1. A motorcycle comprising: a head pipe; a main frame extending in a rearward and downward direction from said head pipe; a power unit mounted to an underside of said main frame; pivot plates provided on a rear portion of said main frame; a rear fork pivotahly mounted to said pivot plates; a rear wheel supported by said rear fork; a muffler disposed between said power unit and said rear wheel and mounted to a lower end portion of one of said pivot plates; and a main stand pivotably mounted to a lower portion of a vehicle body in front of said muffler.

2. A motorcycle according to claim 1 wherein said power unit and said muffler are interconnected via an exhaust pipe, and the exhaust pipe is passed through a region located between left and right upper supported portions of said main stand.

3. A motorcycle according to claim 1 wherein said main stand is supported by a portion of said power unit located below lower ends of said pivot plates.

4. A motorcycle according to claim 1 wherein said main stand is disposed so as to overlap with said muffler as viewed in plan.

5. A motorcycle according to claim 4 wherein said muffler has a concavely- recessed portion formed in an underside thereof for preventing an interference between said muffler and said main stand.

6. A motorcycle comprising: a head pipe; a main frame extending in a rearward and downward direction from said head pipe; a power unit mounted to an underside of said main frame; pivot plates provided on a rear portion of said main frame; a rear fork pivotably mounted to said pivot plates; a rear wheel supported by said rear fork; and a muffler disposed between said power unit and said rear wheel, said muffler having an L shape, as viewed in plan, which comprises a wide front section having received therein an end portion of an exhaust pipe connected to said power unit and a longitudinally-elongated rear section having received therein a separator and communicating pipe, the separator partitioning an interior of said muffler to form a plurality of expansion chambers, the expansion chambers communicating with each other via the communicating pipe, the exhaust pipe having an end opening located above a rear end of a tail pipe of said muffler.

7. A motorcycle according to claim 6 wherein the communicating pipe has openings located above the rear end of the tail pipe.

8. A motorcycle comprising: a head pipe; a main frame extending in a rearward and downward direction from said head pipe; a power unit mounted to an underside of said main frame; pivot plates provided on a rear portion of said main frame; a rear fork pivotably mounted to said pivot plates; a rear wheel supported by said rear fork; a muffler disposed rearwardly of said power unit; an exhaust pipe connecting said power unit and said muffler; and a catalytic converter provided in an intermediate portion of said exhaust pipe in front of a crankcase of said power unit, said catalytic converter extending along a front-rear direction of a cylinder of said power unit as viewed in plan.

9. A motorcycle according to claim 8 wherein said catalytic converter is disposed in overlapping relation to the cylinder as viewed in plan.

10. A motorcycle according to claim 8 wherein said muffler is disposed between said power unit and said rear wheel.

11. A motorcycle according to claim 8 wherein the cylinder extends substantially in a horizontal direction.

12. A motorcycle according to claim 8 wherein said muffler has an L shape, as viewed in plan, which comprises a wide front section having received therein an end portion of an exhaust pipe connected to said power unit and a longitudinally-elongated rear section having received therein a separator and communicating pipe, the separator partitioning an interior of said muffler to form a plurality of expansion chambers, the expansion chambers communicating with each other via the communicating pipe, and said exhaust pipe has an end opening located above a rear end of a tail pipe of said muffler.

13. A motorcycle according to claim 12 wherein the communicating pipe has openings located above the rear end of the tail pipe.