JPH04339089A - Intake device for motorcycle - Google Patents

Abstract

PURPOSE:To enable mass concentration of apparatuses mounted on a vehicle body as well as to provide an air feeding system capable of smoothing feed air flow. CONSTITUTION:In an air intake system for a motorcycle, a main frame 21 is formed in a wide configuration in a side view and in the configuration of an upper wall of a crank case 6, a recess part 6a is formed between a clutch 12 and a kick shaft 13, and a carbureter 7 is arranged in a space surrounded by the recess part 6a, the main frame 21 and a rear shock absorber 11.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake system for a motorcycle, which concentrates the mass of parts mounted on a vehicle body and smooths the flow of intake air.

0002

[Prior Art] In a motorcycle with only one rear shock absorber installed in the center of the vehicle width, when a rear intake structure is adopted in which the carburetor is placed behind the engine, Japanese Patent Laid-Open No. 61-11
As described in Japanese Patent No. 0686, the arrangement of the carburetor forces the rear shock absorber and the main frame to be moved upward, and the seat also has to be moved upward accordingly.

[0003] In other words, since the parts mounted on the car body are arranged in such a way that the mass is dispersed, this is a disadvantage, especially in the case of car models such as trial cars that require further improvement in maneuverability. do not have. Additionally, because the carburetor is placed above the crankcase, there is a step between the carburetor discharge port and the engine intake port, which creates a large bend in the intake passage from the carburetor discharge port to the engine intake port. (See FIG. 3 of Japanese Patent Application Laid-Open No. 110686/1986). As a result, the large bend in the intake passage increases intake resistance, resulting in a reduction in engine output.

0004

SUMMARY OF THE INVENTION It is an object of the present invention to provide an intake system for a motorcycle, which concentrates the mass of parts mounted on a vehicle body and smoothes the flow of intake air.

[0005]

[Means for Solving the Problems] The present invention achieves the above object by mounting an engine below the middle of a pair of left and right main frames, arranging a carburetor behind the engine, and disposing the engine in the crankcase of the engine. In a motorcycle that is provided with a clutch on the side and a kick shaft above the rear thereof, and a rear shock absorber is provided diagonally in the center of the vehicle width behind the crankcase, the main frame is made to have a wide shape in side view. At the same time, a recess is formed in a region between the clutch and the kick shaft on the upper wall of the crankcase, and the carburetor is disposed in a space surrounded by the recess, the main frame, and the rear shock absorber. The present invention is characterized in that the carburetor is communicated with the intake port of the engine.

[0006] In this way, a recess is formed in the area between the clutch and kick shaft on the upper wall of the crankcase, which was generally straight in the past, and the lower part of the carburetor is lowered into this recess, so that the rear It becomes possible to move the shock absorber and main frame downward, allowing for mass concentration. Furthermore, as a result of the carburetor being moved downward, there is no need to greatly change the bend of the intake passage to the engine intake port, and the flow of intake air becomes smoother. Furthermore, by making the main frame wider in side view, the carburetor can be protected from flying stones and the like.

[0007]

[Example] In the motorcycle shown in Figs. 1 to 3, 1 is a body frame, 2 is an engine, 3 is a rear arm pivotally supported at the rear of the body frame 1, and 4 is pivotally supported at the rear end of the rear arm 3. The rear wheel, 5, is a seat. The vehicle body frame 1 includes a pair of left and right main frames 21 extending diagonally backward from a head pipe 20, a down tube 22 extending diagonally downward from the front end of the main frame 21, and the like. The main frame 21 is wide in side view and has a hollow rectangular cross section (see FIG. 3). The rear parts of the left and right main frames 21, 21 are connected and reinforced with a cross member 24, and the left and right seat rails 23, 23 are also connected and reinforced with a cross member 25.

The engine 2 mounted on the vehicle body frame 1 has a crankcase 6 at the bottom.
A carburetor 7 is arranged above the rear part of the vehicle. This vaporizer 7
The discharge side is connected to the intake port 2a of the engine 2 through an intake pipe 8, and the intake side is connected to an air cleaner 10 through an intake pipe 9. Furthermore, a rear shock absorber 1 is installed behind the carburetor 7.
1 is provided so as to pass diagonally through the center of the vehicle width. The rear shock absorber 6 has a lower end connected to the rear arm 3 and an upper end connected to the vehicle body frame 1.

The crankcase 6 is provided with a clutch 12 (details not shown) on one side (right side) that transmits power from an internal crankshaft to a transmission (both not shown). A kick shaft 13 operated by a kick lever 14 is provided at the upper rear part. Further, the upper wall of the crankcase 6 is formed with a recess 6a in a region between the clutch 12 and the kick shaft 13.

In the above structure, the carburetor 7 is arranged in a space surrounded by the upper wall of the crankcase 6, the main frame 21, and the rear shock absorber 11, and its lower part is connected to the recess in the upper wall of the crankcase. 6a, and is installed so as to be offset to the right from the center of the vehicle width. Due to this arrangement, the entire carburetor is moved lower than the installation position in conventional general motorcycles.

[0011] As the position of the carburetor 7 has been moved downward compared to conventional motorcycles, the main frame 21 and rear shock absorber 11 can be installed at a low position as close to the engine 2 as possible. It is possible to centralize mass. Therefore, it is possible to further improve the maneuverability of the motorcycle. In addition, the intake passage from the outlet of the carburetor 7 to the intake port 2a of the engine 2 can be made into a nearly horizontal straight line without making a large bend, which smooths the flow of intake air and improves engine output. can.

As described above, according to the present invention, the maneuverability of the vehicle can be improved, and the output can also be increased, so it is of course applicable to general motorcycles, and is particularly applicable to trial vehicles that drive on rough terrain. This is advantageous when

[0013]

As described above, according to the present invention, a recess is formed in the area between the clutch and the kick shaft on the upper wall of the crankcase, and the lower part of the carburetor is placed in this recess so that the rear The shock absorber and main frame can be moved downward, allowing for further centralization of mass. Furthermore, as a result of the carburetor moving downward, the curvature of the intake passage to the engine intake port does not change significantly, and the flow of intake air can be made smooth. Additionally, since the main frame has a wide shape when viewed from the side, the carburetor can be protected from flying stones.

[0014]

[Brief explanation of the drawing]

FIG. 1 is a side view showing essential parts of a motorcycle according to an embodiment of the present invention.

FIG. 2 is a plan view of the motorcycle in FIG. 1 with the upper side removed.

FIG. 3 is a sectional view taken along the line III-III in FIG. 1;

[Explanation of symbols]

1 Body frame 2 Engine 2a Intake port 3 Rear arm 6 Crankcase 6a Recess 7 Carburetor 8, 9
Intake pipe 11 Rear shock absorber 12 Kick shaft 13 Clutch 20 Head pipe 21 Main frame

Claims (1)

[Claims] Claim 1: An engine is mounted below the middle of a pair of left and right main frames, a carburetor is arranged behind the engine, a clutch is mounted on the side of the crankcase of the engine, and a kick shaft is mounted above the rear part of the engine. In the motorcycle, the main frame has a wide shape in side view, and the clutch and the kick on the upper wall of the crankcase are provided. A recess is formed in a region between the shaft and the carburetor is disposed in a space surrounded by the recess, the main frame, and the rear shock absorber, and the carburetor is communicated with the intake port of the engine. Motorcycle intake system.