Aspects of the present invention relate to methods of stop/start of an internal combustion engine provided with a CVVL system; also a control unit and a vehicle for employing the methods.

An actuation system for a valve is disclosed. The actuation system comprises a housing having an end wall. A first piston and a second piston is slidably positioned within the housing. The second piston is positioned between the first piston and the end wall. A piston rod is coupled to the first piston and slidably extends through the second piston and the end wall. The piston rod is configured to be coupled with the valve. A first spring is arranged between the first piston and the second piston. Further, a second spring is arranged between the second piston and the end wall. The first spring and the second spring are configured to bias the valve to a closed position.

Systems and apparatuses include an engine including a fuel tank, a carburetor including a throttle valve movable between a first throttle position and a second throttle position, a governor system configured to move the throttle valve, and a speed control system including a control lever defining a first actuation distance, and a bellcrank movable between an idle position and a high speed position and coupled to the governor system. The bellcrank defining a second actuation distance that is different than the first actuation distance.

The engine shut-off valve system includes a housing, a gate member, a rotating lever, a locking piston assembly, and a closing piston assembly. The system is installed in fluid connection with a flow line so that air flow passes through a passageway in the housing with the gate member in the locked configuration. The air flow through the passageway stops with the gate member in the closed configuration. The gate member has an asymmetry so that the forces of the spring of the closing piston assembly and the spring of the locking piston assembly are cooperative to actuate between the closed configuration and the locked configuration, while wearing on the gate member differently so as to extend the working life of the valve system. The closing piston assembly and the locking piston assembly are separately accessible for maintenance.

An engine includes a catalyst disposed inside an exhaust passage that guides exhaust discharged from a combustion chamber and a controller programmed to control a throttle valve and a fuel injector. If the engine is overheating, the controller is programmed to control the opening degree of the throttle valve or the injection amount of fuel from the fuel injector to decrease the rotational speed of the crankshaft and to control the injection amount of fuel from the fuel injector to set a target air-fuel ratio to a value richer than a stoichiometric air-fuel ratio.

A vehicle includes: a driving source; a rotation sensor that detects a rotational speed of the driving source; control circuitry; and an actuator that operates the driving source. When the rotational speed of the driving source has exceeded a preset upper threshold, the control circuitry executes suppression control that suppressed an output power of the driving source in comparison with before the rotational speed of the driving source exceeds the upper threshold. In the suppression control, the control circuitry gives to the actuator a command that makes the output power of the driving source suppressed in comparison with before the suppression control is executed, in accordance with an excess degree set in relation to an excess time period that is a time period in which the rotational speed of the driving source has exceeded the upper threshold.