Engine-driven working machine

An engine-driven working machine comprising:

• an engine;
• an actuating part driven by the engine;
• a centrifugal clutch disposed between the engine and the actuating part;
• and
• a controller detecting a rotational speed of the engine to control the rotational speed,
• wherein the engine has a carburetor including a throttle valve,
• wherein when the rotational speed of the engine is higher than a predetermined clutch-in rotational speed, the centrifugal clutch connects the engine with the actuating part so as to transmit rotations of the engine to the actuating part, and
• wherein in a fast idling state in which the engine is operated while a throttle valve of a carburetor of the engine is maintained in a half-opened position, the controller is operated from starting of the engine in a rotational speed limitation mode in which the engine is prevented from rotating at a rotational speed that is higher than a predetermined limitation rotational speed by appropriately performing misfiring cycles,
• further comprising a muffler containing a catalyst for purifying exhaust gas of the engine,
• wherein the controller 18 forces to stop the engine after a predetermined period has passed, during which the engine operates in the rotational speed limitation mode.