Abstract: An intake system for an internal combustion engine in which the inflow characteristic of a mixture of gas is varied by a partition wall provided replaceably in an intake port opening, whereby the output characteristic of the internal combustion engine is regulated to a desired condition, and a vehicle having appropriate operating characteristics is provided. A replaceable partition wall A is mounted in an intake port opening 1a of an internal combustion engine. The partition wall A is composed of a plate P that differs in length as compared to other plates. The plate P is inserted into an upper-lower pair of grooves provided in the intake port opening 1a, whereby the plate P is replaceably mounted, and the inflow characteristic of a mixture of gas sucked in through the intake port opening 1a is varied by replacement of the plate P thus mounted, whereby the output characteristic of the internal combustion engine is regulated to a desired condition.

Abstract: An intake system for an internal combustion engine in which the inflow characteristic of a mixture of gas is varied by a partition wall provided replaceably in an intake port opening, whereby the output characteristic of the internal combustion engine is regulated to a desired condition, and a vehicle having appropriate operating characteristics is provided. A replaceable partition wall A is mounted in an intake port opening 1a of an internal combustion engine. The partition wall A is composed of a plate P that differs in length as compared to other plates. The plate P is inserted into an upper-lower pair of grooves provided in the intake port opening 1a, whereby the plate P is replaceably mounted, and the inflow characteristic of a mixture of gas sucked in through the intake port opening 1a is varied by replacement of the plate P thus mounted, whereby the output characteristic of the internal combustion engine is regulated to a desired condition.

Abstract: To provide a two-cycle internal combustion engine capable of preventing the blow-by phenomenon to improve fuel economy and attain a high exhaust gas purifying performance, and increasing the responsiveness of fuel injection volume. In a two-cycle internal combustion engine, a chamber is disposed in scavenging passages for communicating a crank chamber to a combustion chamber, sealable control valves are respectively disposed in an inlet and an outlet of the chamber, and a fuel feeding system for the supply of fuel into the chamber is provided. The chamber is communicated to one scavenging passage out of a plurality of parallel scavenging passages. The combustion chamber side control valve disposed at an outlet of the chamber on the downstream side of the crank case side control valve provided at an inlet of the chamber, is positioned at the bottom portion of a scavenging passage communicated to the chamber.

Abstract: To provide a compact two-cylinder engine in which adjacent cylinders are located close to each other. In the two-cycle engine of the present invention, the scavenging passages of scavenging ports adjacent to the exhaust ports are flat or elongate in their cross section and extend to the sides of the exhaust ports. This structure allows the cross-sectional area of the scavenging passages to be sufficient, but allows the width of the cylinder section between adjacent cylinders to be decreased. Furthermore, in the two-cycle engine of the present invention, the exhaust passages of the cylinders are arranged in the direction substantially orthogonal with the direction of alignment of the cylinders, and the exhaust control valves are positioned near the exhaust ports in order to control an opening amount of the exhaust ports.