JP2002337778A - Motorcycle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To positively cool a carburetor with travel air while improving the rigidity of a body frame by reducing the size of a bleeder formed in the body frame. SOLUTION: The carburetor 25 and an air cleaner 63 are arranged being distributed on one side and the other side in a cross direction, and the carburetor 25 is positioned on the front side of a body and arranged in a longitudinal direction. A bleeder 88 opened obliquely backward is formed at a part corresponding to a connection part between the carburetor 25 and an intake duct 64 at a side wall of the body frame 2 close to the carburetor 25.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motorcycle having a carburetor and an air cleaner housed in a body frame.

[0002]

2. Description of the Related Art A conventional motorcycle of this type is disclosed, for example, in Japanese Patent Application Laid-Open No. 2000-280962. In the motorcycle body frame disclosed in this publication, a down frame extending rearward and downward from a head pipe and a seat frame extending upward from the rear end of the down frame are integrally formed by casting. Casting is performed using a mold that separates vertically.

[0003] For this reason, the down frame is opened downward by closing the rear and both right and left sides by projecting the projection of the lower mold from below into the recess of the cavity of the upper mold. It is formed in an inverted U-shaped cross section.
Further, in this motorcycle, an engine is mounted below the down frame so that a cylinder is directed forward of the vehicle body, and a carburetor and an air cleaner are housed inside the down frame.

[0004]

In the conventional motorcycle constructed as described above, there has been a problem that the temperature of the carburetor rises, the charging efficiency of the intake air decreases, and the output of the engine decreases. The temperature of the vaporizer rises
This is because traveling wind cannot flow in the down frame of the body frame, and air warmed by the engine stays in the down frame.

In order to solve such a problem, a ventilation hole may be formed in the down frame so that the traveling wind is discharged from the down frame to the outside through the ventilation hole. However, forming the ventilation holes in the vehicle body frame has a new problem that the rigidity of the vehicle body frame is reduced.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is possible to reliably cool a carburetor by running wind while reducing the size of a ventilation hole formed in a vehicle body frame to improve the rigidity of the vehicle body frame. The purpose is to be.

[0007]

In order to achieve this object, a motorcycle according to the present invention distributes a carburetor and an air cleaner to one and the other in the vehicle width direction, and positions the carburetor in front of the vehicle body. The carburetor and the air cleaner are arranged side by side in the front-rear direction, and open obliquely rearward at a portion corresponding to a connection between the carburetor and the air cleaner intake duct on the side wall of the vehicle body frame close to the carburetor. A vent is formed.

According to the present invention, the traveling wind passage having the vent as the outlet is formed in the vehicle body frame, and the traveling wind flows through the vehicle body frame during traveling. Since the airflow is formed at one end in the vehicle width direction and the other end is blocked by an intake duct or an air cleaner, the traveling wind is generated at one end in the vehicle width direction where the airflow hole is formed. The flow rate is relatively high. Since the carburetor is located at a position where the flow rate increases, the carburetor can be efficiently cooled by the traveling wind. In addition, since the operation of connecting the intake duct to the carburetor can be performed from the vent, the number of openings formed in the vehicle body frame can be reduced as compared to the case where an opening exclusively for performing the operation is formed.

A motorcycle according to a second aspect of the present invention is the motorcycle according to the first aspect of the present invention, wherein the adjusting screw of the carburetor is exposed from the vent. According to the present invention, maintenance of the vaporizer can be performed from the vent.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a motorcycle according to the present invention will be described below in detail with reference to FIGS. FIG. 1 is a side view of a motorcycle according to the present invention, FIG. 2 is an enlarged side view showing an engine mounting portion, and FIG. 3 is a side view showing an engine mounting portion of a body frame, and FIG. It is drawn in a state. FIG. 4 is a plan view showing the engine and a part of the body frame, and FIG. 4 is drawn with a part of the body frame broken. FIG. 5 is a sectional view taken along line V-V of a part of the vehicle body frame and the engine in FIG. 2, and FIG. 6 is a sectional view taken along line VI-VI of a part of the body frame and the engine in FIG.

FIG. 7 shows a VII-V of the vehicle body frame in FIG.
8 is a cross-sectional view of the head pipe, and FIG. 9 is an enlarged cross-sectional view showing a front support portion of the fuel tank.
10 and 11 are views showing another example of forming the head pipe. FIG. 12 is a cross-sectional view of the vehicle body frame and the air cleaner, and a broken position in FIG. 12 is indicated by a line XII-XII in FIG. 13 (a) is a side view showing a state where the cover is fixed to a vehicle body frame, FIG. 13 (b) is a top view of the cover, and FIG. 13 (c) is a cover viewed from the left side of the vehicle body. It is a side view. 14A and 14B are views showing an exhaust port cover of the vehicle body frame, wherein FIG. 14A is a front view and FIG.
Is a sectional view taken along the line BB in FIG. 7A, FIG. 7C is a sectional view taken along the line CC in FIG. 7A, and FIG.
It is DD sectional drawing in the figure.

In these figures, the reference numeral 1 denotes a motorcycle according to the present embodiment. Reference numeral 2 denotes a body frame 2, 3 denotes an engine, 4 denotes a front wheel, 5 denotes a front fork, 6 denotes a steering wheel, 7 denotes a rear wheel, 8 denotes a rear arm, 9 denotes a cushion unit, 10 denotes a seat, and 11 denotes a seat. 2 shows a fuel tank.

The front fork 5 is of a telescopic type and is rotatably supported by a head pipe 12 of a body frame 2 described later. The rear arm 8 includes a left arm 8a and a right arm 8 on both sides of the rear wheel 7.
b (see FIG. 6), and the pivot shaft 1
3 (see FIGS. 2 and 6) so as to be rotatable. The cushion unit 9 is interposed between the middle of each of the arms 8 a and 8 b of the rear arm 8 and the body frame 2.

As shown in FIG. 1, the vehicle body frame 2 includes the head pipe 12, a down frame 14 extending rearward and downward from the head pipe 12, and a seat frame extending upward from the rear end of the down frame 14. 15 and a rear frame 16 (see FIGS. 2 and 3) extending downward from the rear end of the down frame 14 are integrally formed. More specifically, as shown in FIGS. 5, 7 and 8, the vehicle body frame 2 is formed by joining a left body half 21 and a vehicle right half 22 by friction stir welding. ing.

The two halves 21 and 22 are formed by casting, respectively, and the left half 21 of the vehicle body has a cross-sectional shape opened toward the right side of the vehicle, and the right half 22 of the vehicle body has It has a cross-sectional shape that is open toward the left side of the vehicle body. That is, a mold (not shown) for molding these two halves 21 and 22 has a cavity formed by a concave portion and a convex portion, and a female mold having a concave portion and a male mold having a convex portion. Uses a structure that comes and goes in the vehicle width direction.

As shown in FIGS. 5, 7 and 8, the left half portion 21 of the vehicle body has a ridge 21a formed on the inner edge of the vehicle body, and the right half portion 22 of the vehicle body has the inner edge portion. A groove 21b into which the ridge 21a fits is formed on the edge. In order to join these two halves 21 and 22 to each other, the concave groove 21b and the ridge 21a are fitted and overlap each other in the thickness direction, and in this state, a rotary tool for friction stir welding is brought into contact with the outer surface. By doing it. After the joining, a hole 12a (see FIG. 8) in the head pipe 12 is drilled by machining to adjust the head pipe 12 to a predetermined size. In this embodiment, as shown in FIG. 5, an edge portion of the right half portion 22 of the vehicle body forming the concave groove 21b is formed so as to be thicker than other portions. This is to prevent the joint from being deformed by buckling due to being pressed by the rotating tool when performing friction stir welding.

The head pipe 12 can be formed as shown in FIGS. 10 and 11 in addition to the above-described one. 10 and 11 show another example of forming the head pipe. FIG. 10 (a) is a plan view and FIG.
(B) is a longitudinal sectional view. In the head pipe shown in FIG. 10, rings 12b for press-fitting bearings are fixed to the upper and lower openings. The ring 12b can be fixed to the head pipe 12 by a friction stir welding method, brazing, welding, or the like.

After the ring 12b is fixed to the head pipe 12, the inner peripheral portion is finished by honing or the like. The shape of the inner peripheral surface of the ring 12b before the finishing is performed is indicated by a two-dot chain line in FIG. 10B, and the part to be finished is indicated by the finishing symbol in FIG. 10B. By press-fitting a bearing for supporting the steering shaft into the ring 12b, it is possible to prevent a load at the time of press-fitting from being applied to the head pipe 12. Therefore, the steering shaft (not shown) can be firmly supported while employing a structure in which the head pipe 12 is formed by the left and right halves 21 and 22. In FIG. 10B, what is indicated by reference numeral 12c facing the inside of the head pipe 12 is an inner flange for positioning the ring 12b in the axial direction. The inner flange 12c is formed integrally with the left and right halves 21 and 22, respectively. The head pipe 12 shown in FIG. 11 is formed separately from the left and right halves 21 and 22 and is welded to these two halves. The weld is indicated by reference numeral 12d.

By joining the left half 21 and the right half 22 of the vehicle body in this way, a hollow portion 23 is formed inside the vehicle body frame 2. In the vehicle body frame 2, a portion other than the middle portion 24 in the front-rear direction corresponding to the front portion of the engine 3 is formed in a closed cross-sectional shape.
Auxiliary devices such as the fuel tank 11 and the carburetor 25 are inserted and mounted in the device 3.

As shown in FIG. 5, the intermediate portion 24 is formed in a U-shaped cross section and is opened downward, and a cross member 26 is provided at a lower end opening 24a with the left half 21 of the vehicle body and the vehicle body. It hangs over the right half 22 and is laid horizontally. As shown in FIGS. 2, 4 and 5, a front bracket 27 for supporting the front part of the engine is attached to both ends of the cross member 26 in the vehicle width direction by bolts 28 for attaching the cross member.

The mounting bolts 28 are screwed from below into mounting seats 29 of the left and right halves 21 and 22 so that they can be easily attached and detached from the lower end opening. A coil 31 is mounted on the upper surface of the right side (the left side in FIG. 5) of the cross member 26 via a coil bracket 30. This coil 31 is for supplying power to the ignition plug P of the engine 3.

In FIG. 5, the reference numeral 32 provided above the cross member 26 is a bracket for supporting the rear end of the fuel tank 11. This bracket 32 is formed in a gate shape that is opened downward,
Both ends are fixed to the left and right halves 21 and 22 of the body frame 2 by fixing bolts 33. These fixing bolts 33 are attached to the mounting seats 3 of the two halves 21 and 22 from the inside of the vehicle body.
4 screwed.

In this embodiment, of the left and right fixing bolts 33, the fixing bolts 33 on the left side of the vehicle body are used.
The fuel cock support bracket 35 and the fuel tank support bracket 32 are fastened together to the left half 21 of the vehicle body. The fuel cock attached to the fuel cock supporting bracket 35 is indicated by reference numeral 36 in FIG.

The fuel tank 11 is formed by a blow molding method or a rotational molding method using synthetic resin as a material. The fuel tank supporting bracket 32 supports the rear end of the fuel tank 11 and the front end of the fuel tank 11 is supported by the down frame 14 of the vehicle body frame 2. Have been supported. The rear end of the fuel tank is supported by attaching a grommet 37 to the bracket 32 and fitting a support projection 38 projecting downward from the rear end of the fuel tank into a support hole 37a of the grommet 37 from above. Is going.

As shown in FIG. 9, the front end of the fuel tank is supported by screwing a fixing nut 40 to a cylindrical member 39 integrally projecting from the fuel tank 11 by insert molding. And flange 3 at the base of the tubular member
9a by sandwiching the supporting cylinder 42 of the vehicle body frame 2 via the sealing member 41. In FIG. 9, reference numeral 43 denotes a fueling cap.

The engine 3 of the motorcycle 1 is a four-cycle air-cooled single-cylinder engine. As shown in FIG. 2, a cylinder 3a is disposed so that an axis is directed in the front-rear direction of the vehicle body, and is provided in a crankcase 3b. 3 mounting bosses 5
1 to 53 are mounted on the vehicle body frame 2 by mounting bolts 54 to 56, respectively. The power of the engine 3 is transmitted from the output sprocket 57 provided at the left end of the vehicle body of the crankcase 3b to the rear wheel 7 via a chain (not shown). In this embodiment, the engine 3 is covered with an engine cover 58 in a state where the engine 3 is mounted on the vehicle body frame 2 as shown in FIG.

An intake pipe 61 is provided above the cylinder 3a.
The carburetor 25 is connected via a, and an exhaust pipe 62 is connected to the lower part of the cylinder 3a. The intake pipe 61 is formed so as to be inclined so as to gradually extend toward the rear of the vehicle body as it goes upward, and extends above the cross member 26 from the lower end opening of the halfway portion 24 of the body frame 2. ing. The carburetor 25 connected to the rear end of the intake pipe 61 is disposed behind the cross member 26 and connects to an intake duct 64 of an air cleaner 63 described later.

Of the three bosses 51 to 53 for attaching the engine 3 to the body frame 2, the front boss 51 at the front end of the crankcase is attached to the front bracket 27 for supporting the engine, which extends downward from the cross member 26. The upper boss 52 and the lower boss 53 at the rear end of the crankcase are mounted to the rear frame 16 of the vehicle body frame 2 via a rear bracket 65 for supporting the engine.

As shown in FIG. 6, a damper rubber 66 is interposed between the front boss 51 and the mounting bolt 54 and between the upper boss 52 and the mounting bolt 55. FIG. 6 shows a connecting portion between the upper boss 52 and the mounting bolt 55, but a connecting portion between the front boss 51 and the mounting bolt 54 has a structure equivalent to the structure shown in FIG. The other boss 53 is rigidly fixed to the rear bracket 65 via a mounting bolt 56. By interposing the damper rubber 66 at two of the three mounting portions in this manner, the vibration of the engine 3 transmitted to the vehicle body frame 2 can be reduced while the engine 3 is firmly supported. In addition to the structure of this embodiment, the engine 3 is mounted on the vehicle body frame 2 by fixing three bosses rigidly to the vehicle body frame 2 or by elastically supporting the upper boss 52 and the lower boss 53 on the front side. The boss 51 is rigidly fixed, the upper boss 51 is rigidly fixed by elastically supporting the front boss 51 and the lower boss 53, and the other boss is elastically supported by any one of the three bosses. Can be rigidly fixed, or all the bosses can be elastically supported, or can be appropriately changed.

As shown in FIG. 2, the rear bracket 65 for mounting the upper boss 52 and the lower boss 53 is formed in a plate shape, and two fixing bolts 67, 68 and the pivot shaft 13. The material forming the rear bracket 65 is steel,
Various materials such as an aluminum alloy, a magnesium alloy, and a fiber-reinforced plastic can be used. The rear frame 16 constitutes a part of the rear end of the down frame 14, and as shown in FIGS. 3 and 6, side walls 16a and 16b at both ends in the vehicle width direction, a front wall 16c, and a rear wall. Wall 1
6d and the bottom wall 16e are formed so as to be opened upward. Since the upper open portion of the rear frame 16 is closed by the down frame 14 of the vehicle body frame 2, the rear frame 16 has a closed cross-sectional shape as a result.

The rear frame 16 is formed integrally with cylindrical bosses 69 and 70 extending from one end to the other end in the vehicle width direction. The cylindrical bosses 69 and 70 support the pivot shaft 13. are doing. The pivot shaft 13 has a flange 13a integrally formed on one end and a nut 71 screwed on the other end. The pivot shaft 13 is provided between the flange 13a and the rear frame 16, and between the nut 71 and the rear frame 16. The nut 71 is fastened to the rear frame 16 in a state where the rear bracket 65 is sandwiched between them. The left arm 8a and the right arm 8b of the rear arm 8 are rotatably supported at both ends of the pivot shaft 13.

The air cleaner 63 is shown in FIGS.
As shown in FIG. 2, the right half 22 of the vehicle body frame 2
An air cleaner case 81 formed integrally with the air cleaner case 81; a cover 83 for closing an air cleaner element attachment / detachment opening 82 formed at the right end of the air cleaner case 81; It comprises an element 84 and a flame-extinguishing net 84a disposed inside the air cleaner element 84.

The air cleaner case 81 is formed so that a portion where the down frame 14 and the seat frame 15 in the right half portion 22 of the vehicle body are connected to each other is partially recessed toward the inside of the vehicle body. The attachment / detachment opening 82 is formed in a bottomed cylindrical shape so as to open toward the right of the vehicle body. This air cleaner case 8
In FIG. 1, an intake outlet 85 is formed at an inner end of the vehicle body to connect the intake duct 64.

The air cleaner case 81 is disposed above the crankcase 3b of the engine 3, and has a lower end connected to a blow-by gas lead-out pipe 86. The pipe 86 is erected upward from the crankcase 3b, and the upper end 86a is inserted into the pipe connecting coupler 87 at the lower end 81a of the air cleaner case 81 from below. The coupler 87 is fixed to the pipe 86 by a clip 87a, and has a structure for preventing blow-by gas from leaking from a pipe connection portion.

The cover 83 is, as shown in FIG.
An air introduction duct 83a is attached to the upper part, and is fixed to the right half portion 22 of the vehicle body frame 2 by three fixing bolts 83b as shown in FIG. The air introduction duct 83a has an upper end portion facing the inside of the body frame 2 and a lower end portion facing the inside of the cover 83.
That is, the air cleaner 63 according to this embodiment includes:
Air in the vehicle body frame 2 flows in through the air introduction duct 83b.

The carburetor 25 connected to the downstream end of the intake duct 64 is disposed closer to the vehicle body left side than the center line C (see FIG. 4) of the motorcycle 1 in the vehicle width direction. That is, in the motorcycle 1, the air cleaner case 81 and the carburetor 25 are disposed separately in one and the other in the vehicle width direction. The center line in the vehicle width direction of the motorcycle 1 is indicated by a dashed line C in FIG.

The left half portion 21 of the vehicle body frame 2 that covers the carburetor 25 from the left side of the vehicle body has a vent 88 formed at a portion corresponding to a connection portion between the carburetor 25 and the intake duct 64. The ventilation hole 88 is formed so as to communicate the inside and outside of the left half 21 with a front wall 89a of a recess 89 formed to partially indent the left half 21 of the vehicle body toward the inside of the vehicle. Also, as shown in FIG.
The opening range is set so that the adjusting screw 25a of the vaporizer 25 is exposed.

As shown in FIG. 4, the concave portion 89 is formed so that the portion located on the innermost side of the vehicle body approaches the intake duct 64, and the front wall 89a of the concave portion 89 moves rearward of the vehicle body. It is inclined so as to gradually extend toward the inside of the vehicle body as it goes. Therefore, the vent 8
8 is open obliquely rearward. By forming the ventilation port 88 and the recessed portion 89 in this manner, the traveling wind flowing in the down frame 14 passes between the carburetor 25 and the half 21 on the left side of the vehicle body, and flows out of the ventilation port 88 to the outside of the frame. Is discharged. The traveling wind is fed by a traveling wind introduction slit 58a formed on the front surface of the engine cover 58 (see FIG. 1).
Flows into the engine cover 58 from the down frame 1
4 flows into the down frame 14 from the lower end opening of the halfway portion 24.

The reference numeral 91 provided in the ventilation opening 88 so as to close the ventilation opening 88 is a cover for preventing foreign substances from entering the inside. As shown in FIG. 14, the cover 91 includes a frame 91a formed in a shape equivalent to the shape of the opening of the ventilation port 88, and a number of bars 91b laid horizontally on the frame 91a. Frame 91
In FIG. 14 (a), a projection 91c is projected from a rear end and a lower end, and a hook 91d {see FIG. 14C} is projected from a front. As shown in FIG. 14 (d), the cover 91 engages with the projection 91c in the lateral hole 88a of the ventilation hole 88, and as shown in FIG.
By engaging 1d with the opening edge of the ventilation opening 88,
It is detachably attached to the ventilation opening 88.

In the motorcycle 1 configured as described above, the operation of attaching the engine 3 to the body frame 2 is as follows.
This is performed after the fuel tank 11 is attached to the down frame 14. As shown in FIGS. 5 and 9, the fuel tank 11 is attached to the vehicle body frame 2 by attaching a support bracket 32 to the rear end of the fuel tank 11 in advance, and a cylindrical member 39 at the front end of the fuel tank. Is fixed to the front portion of the down frame by the fastening structure. Next, the bracket 32 is fixed to the down frame 14 together with the fuel cock 36 by the fixing bolt 33. Fuel cock 36 and fuel tank 1
A fuel hose (not shown) connecting the fuel tank 1 and the fuel tank 11 is attached before the fuel tank 11 is inserted into the down frame 14.

To mount the engine 3 on the vehicle body frame 2, first, the front bracket 27 is fixed to the front boss 51 at the front end of the crankcase with mounting bolts 54, and the cross member 26 is temporarily assembled to the front bracket 27. . The engine 3 includes an intake pipe 61 and a carburetor 2.
5 is attached in advance. Note that the connection between the carburetor 25 and the intake duct 64 is established after the engine is mounted.
From the body frame 2 into the body.

Next, the front bracket 27, the cross member 26, the carburetor 25 and the like are inserted into the vehicle body frame 2 from the lower end opening of the halfway portion 24 of the vehicle body frame 2, and the upper boss 52 at the rear end of the engine and The lower boss 53 and the rear bracket 65 are temporarily held by the mounting bolts 55 and 56. With the engine 3 temporarily held on the body frame 2 in this manner, the front bracket 27 and the cross member 26 are fixed to the down frame 14 by the mounting bolts 28. Then, the upper boss 52 and the lower boss 53 are fastened to the rear bracket 65 by the fixing bolts 55 and 56 with a regular tightening force.
The engine mounting operation is completed. Also, as described above, the blow-by gas lead-out pipe 86 of the crankcase 3 b is connected to the coupler 87 of the air cleaner case 81 by attaching the engine 3 to the vehicle body frame 2 from below. The air cleaner 63 includes an air cleaner case 81.
The air cleaner element 84 is mounted from the outside of the vehicle body to the air cleaner element attachment / detachment opening 82, and the cover 83 is attached to the air cleaner element 84 for assembly.

In the motorcycle 1 configured as described above, the carburetor 25 and the air cleaner 63 are disposed separately on one side and the other in the vehicle width direction, and the carburetor 25 is positioned on the front side of the vehicle body and is arranged in the front-rear direction. The vaporizer 2 is disposed side by side.
5 on the side wall of the body frame 2 close to
A ventilation opening 88 that opens diagonally rearward is formed in a portion corresponding to a connection portion between the vehicle and the intake duct 64, so that a traveling wind passage having the ventilation opening 88 as an outlet is formed in the vehicle body frame 2, The traveling wind flows in the body frame 2 during traveling.

Since the airflow is formed at one end (left end of the vehicle body) in the vehicle width direction and the other end is blocked by the intake duct 64 and the air cleaner 63, At one end in the vehicle width direction where the vent 88 is formed, the flow rate becomes relatively large. Since the vaporizer 25 is located at a portion where the flow rate increases, the vaporizer 25 can be efficiently cooled by the traveling wind. In addition, since the operation of connecting the intake duct 64 to the carburetor 25 can be performed from the ventilation port 88, the number of openings formed in the vehicle body frame 2 can be reduced as compared to the case where an opening for exclusively performing the operation is formed. Can be.

The left half 2 of the vehicle body frame 2
1 and the right half 22 of the vehicle body can be joined by, for example, brazing in order to avoid sticking to the friction stir welding method.
Any method that does not melt the frame may be used. When brazing, the two halves 21,
A brazing material is applied to the joint in a state where 22 is combined, and the brazing material is melted and joined by a heating furnace.

[0046]

As described above, according to the present invention, since a large amount of traveling wind flows around the carburetor, the ventilation holes are formed small in order to improve the rigidity of the body frame. Thus, the vaporizer can be efficiently cooled by the traveling wind. Further, according to the present invention, since the operation of connecting the intake duct to the carburetor can be performed from the ventilation port, the rigidity of the vehicle body frame is further increased as compared with a case where an opening for exclusively performing the operation is formed. Improvement can be achieved.

According to the second aspect of the invention, since the maintenance of the carburetor can be performed from the ventilation port, the rigidity of the vehicle body frame is improved as compared with the case where the hole for performing the maintenance is exclusively formed. Can be.

[Brief description of the drawings]

FIG. 1 is a side view of a motorcycle according to the present invention.

FIG. 2 is an enlarged side view showing an engine mounting portion.

FIG. 3 is a side view showing an engine mounting portion of the vehicle body frame.

FIG. 4 is a plan view showing a part of an engine and a body frame.

FIG. 5 is a sectional view taken along line VV of a part of the vehicle body frame and the engine in FIG. 2;

6 is a sectional view taken along line VI-VI of a part of the vehicle body frame and the engine in FIG. 2;

7 is a sectional view of the vehicle body frame in FIG. 2 taken along line VII-VII.

FIG. 8 is a cross-sectional view of the head pipe.

FIG. 9 is an enlarged sectional view showing a front support portion of the fuel tank.

FIG. 10 is a view showing another example of forming a head pipe.

FIG. 11 is a view showing another example of forming a head pipe.

FIG. 12 is a sectional view of a body frame and an air cleaner.

FIG. 13 is a view showing a cover for an air cleaner.

FIG. 14 is a view showing an exhaust port cover of the vehicle body frame.

[Explanation of symbols]

2 ... body frame, 25 ... carburetor, 25a ... adjusting screw, 63 ... air cleaner, 64 ... duct, 88 ... vent.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yushi Inoue 2500 Shinkai, Iwata-shi, Shizuoka Yamaha Motor Co., Ltd.

Claims (2)

[Claims] 1. A motorcycle in which a carburetor and an air cleaner are housed in a vehicle body frame, the carburetor and the air cleaner are divided into one and the other in a vehicle width direction, and the carburetor is positioned on the front side of the vehicle to vaporize. Vents are arranged side by side in the front-rear direction, and open obliquely rearward at a portion corresponding to the connection between the carburetor and the air cleaner intake duct on the side wall of the body frame close to the carburetor. A motorcycle comprising: 2. The motorcycle according to claim 1, wherein an adjusting screw of the carburetor is exposed from a vent.