Abstract: An engine output control system includes an engine ECU having a fundamental ignition timing map, a fundamental fuel injection quantity map, a target throttle angle determination unit for determining a target throttle angle of an exhaust control valve, an exhaust control valve diagnosis unit for diagnosing operation of the exhaust control valve, an ignition timing map to be used during an abnormality for determining fundamental ignition timing when the exhaust control valve operates abnormally, and an abnormal fuel injection thinning-out table for determining a reduced rate of fuel injection when the exhaust control valve has been diagnosed as abnormal. The exhaust control valve driving unit supplies a driving current to an actuator in such a manner that the target throttle angle notified by the engine ECU coincides with actual valve throttle angle. The system is capable of obtaining sufficient traveling performance even when an exhaust control valve has is operating abnormally.

Abstract: An engine output control system includes an engine ECU having a fundamental ignition timing map, a fundamental fuel injection quantity map, a target throttle angle determination unit for determining a target throttle angle of an exhaust control valve, an exhaust control valve diagnosis unit for diagnosing operation of the exhaust control valve, an ignition timing map to be used during an abnormality for determining fundamental ignition timing when the exhaust control valve operates abnormally, and an abnormal fuel injection thinning-out table for determining a reduced rate of fuel injection when the exhaust control valve has been diagnosed as abnormal. The exhaust control valve driving unit supplies a driving current to an actuator in such a manner that the target throttle angle notified by the engine ECU coincides with actual valve throttle angle. The system is capable of obtaining sufficient traveling performance even when an exhaust control valve has is operating abnormally.

Abstract: To improve the comfortability in riding by discriminating sudden acceleration upon startup before connection of a centrifugal clutch and limiting the engine output power. A supervision starting condition discrimination section discriminates whether or not an engine satisfies a supervision starting condition for starting discrimination of satisfaction of a starting control condition. The supervision starting condition is discriminated based on a vehicle speed, a throttle opening and an engine speed. Particularly, a condition at least of the engine speed from among the parameters such as the vehicle speed is set to a value lower than a speed at which a centrifugal clutch is connected.

Abstract: A revolution number control system includes ignition timing delay controlling means for delaying ignition timing from the ignition advance amount n at first prescribed value n2 when the engine revolution number NE is between the first prescribed value n2 and a clutch-on revolution number n4. The first prescribed value n2 is a predetermined revolution number smaller than a present revolution number and the clutch-on revolution number n4 is the present revolution number, and the revolution number control system 40 controls the revolution number by operating the ignition timing delay controlling means when a throttle opening sensor does not detect a change in the throttle opening.

Abstract: To improve the comfortability in riding by discriminating sudden acceleration upon startup before connection of a centrifugal clutch and limiting the engine output power. A supervision starting condition discrimination section discriminates whether or not an engine satisfies a supervision starting condition for starting discrimination of satisfaction of a starting control condition. The supervision starting condition is discriminated based on a vehicle speed, a throttle opening and an engine speed. Particularly, a condition at least of the engine speed from among the parameters such as the vehicle speed is set to a value lower than a speed at which a centrifugal clutch is connected.

Abstract: A revolution number control system includes ignition timing delay controlling means for delaying ignition timing from the ignition advance amount n at a first prescribed value n2 when the engine revolution number NE is between the first prescribed value n2 and a clutch-on revolution number n4. The first prescribed value n2 is a predetermined revolution number smaller than a preset revolution number and the clutch-on revolution number n4 is the preset revolution number, and the revolution number control system 40 controls the revolution number by operating the ignition timing delay controlling means when a throttle opening sensor does not detect a change in the throttle opening.