Abstract: A general-purpose engine fuel tank fuel vapor treatment system includes: a canister mounted on a peripheral part of a fuel filler opening of a fuel tank mounted on a general-purpose engine, the canister housing a fuel adsorbent for adsorbing fuel vapor generated in the interior of the fuel tank; and an air vent provided in a tank cap fitted into the filler opening of the fuel tank. The air vent has an inner end opening in the interior of the fuel tank, and an outer end opening to the atmosphere. The canister is connected to the air vent. The interior of the fuel tank is made open to the atmosphere via the canister and the air vent. Thus, need for special piping is eliminated and fuel vapor within the fuel tank is treated while always stably maintaining the interior of the fuel tank at atmospheric pressure.

Abstract: A muffler having a muffler body divided into first and second exhaust chambers by a partitioning member which has a third exhaust chamber formed therein. An exhaust inlet introduces exhaust gas from an engine into the first exhaust chamber. First communication bores provide communication between the first and second exhaust chambers, and second communication bores provide communication between the second exhaust chamber and the third exhaust chamber. The third exhaust chamber is open to the atmosphere through an exhaust outlet pipe. An exhaust emission control catalyst is carried on an outer surface of the partitioning member facing the first and second exhaust chambers, as well as on an inner surface of the partitioning member facing the third exhaust chamber. An inner surface of the muffler body does not carry the exhaust emission control catalyst.

Abstract: A general-purpose engine fuel tank fuel vapor treatment system includes: a canister mounted on a peripheral part of a fuel filler opening of a fuel tank mounted on a general-purpose engine, the canister housing a fuel adsorbent for adsorbing fuel vapor generated in the interior of the fuel tank; and an air vent provided in a tank cap fitted into the filler opening of the fuel tank. The air vent has an inner end opening in the interior of the fuel tank, and an outer end opening to the atmosphere. The canister is connected to the air vent. The interior of the fuel tank is made open to the atmosphere via the canister and the air vent. Thus, need for special piping is eliminated and fuel vapor within the fuel tank is treated while always stably maintaining the interior of the fuel tank at atmospheric pressure.

Abstract: A valve operating system includes: a decompression cam member that is provided on a camshaft, and moves between an operative position C where an exhaust tappet is operated in a valve opening direction in a compression stroke and an inoperative position D where the exhaust tappet is released; an exhaust gas recirculation cam member that is provided on the camshaft, and moves between an inoperative position F where the exhaust tappet is released and an operative position G where the exhaust tappet is operated in a valve opening direction in an intake stroke of the engine; and a common centrifugal mechanism that is driven by the camshaft to operate the decompression cam member to the operative position C in a starting rotation region of the engine and to the inoperative position D after the starting, and operate the exhaust gas recirculation cam member to the inoperative position F in a low speed operation region of the engine and to the operative position G in a high-speed operation region.

Abstract: A general-purpose engine includes a canister which adsorbs fuel vapor that has evaporated within a fuel tank. The fuel vapor is desorbed from the canister and guided to an intake system communicating with an engine main body. The engine main body includes a crankcase and a cylinder block joined to the crankcase to have an upwardly inclined cylinder axis (C). The canister is disposed to one side of the crankcase and beneath the cylinder block to avoid any increase in the dimensions of the general-purpose engine.

Abstract: In an exhaust emission control system for an engine, comprising an exhaust emission control catalyst disposed in an exhaust muffler whose inside is divided into a plurality of chambers, at least a portion of the inside of the exhaust muffler is divided into a first chamber for converting mainly NOx in exhaust gas and a second chamber for converting HC and CO in the exhaust gas. The exhaust muffler comprises: a partition wall having a conduit for guiding the exhaust gas from the first chamber to the second chamber; an exhaust gas inlet for introducing the exhaust gas into the first chamber; an external-air suction means for sucking external air into the second chamber; and a discharge pipe for discharging the external air and the exhaust gas flowing through the second chamber.

Abstract: A composite control valve is constructed by a valve housing, first and second diaphragms mounted to the valve housing and disposed to be opposed to each other, a negative pressure working chamber defined between the first and second diaphragms to communicate with a negative pressure generating section in an engine, a first control valve adapted to be opened and closed by advancing and returning of the first diaphragm, and a second control valve adapted to be opened and closed by advancing and returning of the second diaphragm. The first control valve is incorporated into an air vent system for a fuel tank, and the second control valve is incorporated into a fuel passage system extending from the fuel tank to a fuel supply section in the engine.

Abstract: In an engine exhaust muffler with an exhaust emission control function, the inside of a box-shaped muffler body is divided into a first exhaust chamber and a second exhaust chamber by a partitioning member which has a third exhaust chamber formed therein. The muffler body is provided with an exhaust inlet for introducing exhaust gas from an engine into the first exhaust chamber. The partitioning member is provided with first communication bores providing communication between the first and second exhaust chambers, and second communication bores providing communication between the second exhaust chamber and the third exhaust chamber. The third exhaust chamber is open to the atmosphere through an exhaust outlet pipe. An exhaust emission control catalyst is carried on an outer surface of the partitioning member facing the first and second exhaust chambers, as well as on an inner surface of the partitioning member facing the third exhaust chamber.

Abstract: In a general purpose engine, a crankcase is formed from a case main body and a cover secured to the case main body, and a bearing support member is disposed between a drive transmission wheel and a crank web that is at one end in the axial direction. The bearing support member is formed into a shape that allows oil held within the crankcase to flow between opposite sides of the bearing support member and is mounted on the case main body.

Abstract: A valve operating system includes: a decompression cam member that is provided on a camshaft, and moves between an operative position C where an exhaust tappet is operated in a valve opening direction in a compression stroke and an inoperative position D where the exhaust tappet is released; an exhaust gas recirculation cam member that is provided on the camshaft, and moves between an inoperative position F where the exhaust tappet is released and an operative position G where the exhaust tappet is operated in a valve opening direction in an intake stroke of the engine; and a common centrifugal mechanism that is driven by the camshaft to operate the decompression cam member to the operative position C in a starting rotation region of the engine and to the inoperative position D after the starting, and operate the exhaust gas recirculation cam member to the inoperative position F in a low speed operation region of the engine and to the operative position G in a high-speed operation region.

Abstract: A general-purpose engine includes a canister which adsorbs fuel vapor that has evaporated within a fuel tank. The fuel vapor is desorbed from the canister and guided to an intake system communicating with an engine main body. The engine main body includes a crankcase and a cylinder block joined to the crankcase to have an upwardly inclined cylinder axis (C). The canister is disposed to one side of the crankcase and beneath the cylinder block to avoid any increase in the dimensions of the general-purpose engine.

Abstract: A composite control valve is constructed by a valve housing, first and second diaphragms mounted to the valve housing and disposed to be opposed to each other, a negative pressure working chamber defined between the first and second diaphragms to communicate with a negative pressure generating section in an engine, a first control valve adapted to be opened and closed by advancing and returning of the first diaphragm, and a second control valve adapted to be opened and closed by advancing and returning of the second diaphragm. The first control valve is incorporated into an air vent system for a fuel tank, and the second control valve is incorporated into a fuel passage system extending from the fuel tank to a fuel supply section in the engine.

Abstract: In a general purpose engine, a crankcase is formed from a case main body and a cover secured to the case main body, and a bearing support member is disposed between a drive transmission wheel and a crank web that is at one end in the axial direction. The bearing support member is formed into a shape that allows oil held within the crankcase to flow between opposite sides of the bearing support member and is mounted on the case main body.

Abstract: In an exhaust emission control system for an engine, comprising an exhaust emission control catalyst disposed in an exhaust muffler whose inside is divided into a plurality of chambers, at least a portion of the inside of the exhaust muffler is divided into a first chamber for converting mainly NOx in exhaust gas and a second chamber for converting HC and CO in the exhaust gas. The exhaust muffler comprises: a partition wall having a conduit for guiding the exhaust gas from the first chamber to the second chamber; an exhaust gas inlet for introducing the exhaust gas into the first chamber; an external-air suction means for sucking external air into the second chamber; and a discharge pipe for discharging the external air and the exhaust gas flowing through the second chamber.

Abstract: A cam shaft having a cam piece disposed on a locking member or plurality of locking members provided on a shaft at predetermined positions. A recess or recesses formed in the cam piece align with and engage the locking members disposed on the shaft. The cam piece is secured to the shaft by a resin injected into and around the recess such that the cam piece is integrally fixed on the shaft when the resin hardens.