Abstract: An exhaust gas sensor inhibits a detecting part of an exhaust gas sensor from being exposed to water and has high detection accuracy and high durability. The exhaust gas sensor has a sensor body and a protective cover. The sensor body has an outer housing. The outer housing has a plurality of gas inlets. A gas detection element for detecting a component of the exhaust gas (e.g., oxygen) disposed within the outer housing. The protective cover has a cylindrical shape and has a plurality of protrusions at its opposing ends. The protrusions provide a tight fit with the outer housing. The protective cover is attached to the outer periphery of the outer housing without closing gas inlets formed through the outer cylinder by press-fitting the outer cylinder into the protective cover.

Abstract: A watercraft has an exhaust conduit that includes an exhaust gas passage and a cooling water passage. The exhaust gas passage and the cooling water passage are configured to mix together an exhaust gas flow and a cooling water flow at a junction. The mixture is ultimately discharged from the watercraft. The watercraft has an exhaust valve drive system that has a drive motor and a controller. The exhaust valve drive system operates an exhaust control valve to control the flow of exhaust gases through the exhaust conduit. The exhaust control valve includes a pivot shaft extending generally horizontally and attached to a valve body. The exhaust control valve is positioned upstream of the junction. The controller operates the drive motor which drives the exhaust control valve between an open position and closed position. The controller can receive signals from an engine rotation sensor and a throttle opening sensor and can control the drive motor based on these signals.

Abstract: An exhaust gas sensor inhibits a detecting part of an exhaust gas sensor from being exposed to water and has high detection accuracy and high durability. The exhaust gas sensor has a sensor body and a protective cover. The sensor body has an outer housing. The outer housing has a plurality of gas inlets. A gas detection element for detecting a component of the exhaust gas (e.g., oxygen) disposed within the outer housing. The protective cover has a cylindrical shape and has a plurality of protrusions at its opposing ends. The protrusions provide a tight fit with the outer housing. The protective cover is attached to the outer periphery of the outer housing without closing gas inlets formed through the outer cylinder by press-fitting the outer cylinder into the protective cover.

Abstract: A watercraft has an exhaust conduit that includes an exhaust gas passage and a cooling water passage. The exhaust gas passage and the cooling water passage are configured to mix together an exhaust gas flow and a cooling water flow at a junction. The mixture is ultimately discharged from the watercraft. The watercraft has an exhaust valve drive system that has a drive motor and a controller. The exhaust valve drive system operates an exhaust control valve to control the flow of exhaust gases through the exhaust conduit. The exhaust control valve includes a pivot shaft extending generally horizontally and attached to a valve body. The exhaust control valve is positioned upstream of the junction. The controller operates the drive motor which drives the exhaust control valve between an open position and closed position. The controller can receive signals from an engine rotation sensor and a throttle opening sensor and can control the drive motor based on these signals.

Abstract: A jet propulsion unit for a small watercraft including a secondary thrust arrangement. The secondary thrust arrangement includes a primary valve and a secondary valve arrangement. At least one discharge port is disposed on a hull of the watercraft. A jet propulsion unit is configured to discharge pressurized water from the steering nozzle in a substantially rearward direction from the watercraft or to discharge pressurized water through at least one discharge port disposed in the outer surface of the hull to achieve enhanced steering control of the watercraft.

Abstract: A jet propulsion unit for a small watercraft including a secondary thrust arrangement. The secondary thrust arrangement includes a primary valve and a secondary valve arrangement. At least one discharge port is disposed on a hull of the watercraft. A jet propulsion unit is configured to discharge pressurized water from the steering nozzle in a substantially rearward direction from the watercraft or to discharge pressurized water through at least one discharge port disposed in the outer surface of the hull to achieve enhanced steering control of the watercraft.