Stihl FS 70 Instruction Manual - Page 33

English Engine Management Adjusting the Carburetor Spark Plug Exhaust emissions are controlled by the design of the engine and components (e.g. carburation, ignition, timing and valve or port timing). The carburetor has been set at the factory to provide an optimum fuel-air mixture under most operating conditions. Adjusting Idle Speed Engine stops while idling N Warm up the engine for about 3 minutes. N Turn the idle speed screw (LA) slowly clockwise until the engine runs smoothly - the cutting attachment must not run. Cutting attachment runs when engine is idling N Turn the idle speed screw (LA) counterclockwise until the cutting attachment stops moving and then rotate the screw another 1/2 to 3/4 turn in the same direction. 0815BA006 KN If there is a loss of engine power, the machine is difficult to start or runs poorly at idle, first check the spark plug. Install a new spark plug after approximately 100 operating hours or earlier if the electrodes are eroded/corroded. The wrong fuel mix (too much engine oil in the gasoline), a dirty air filter and unfavorable running conditions (mostly at part throttle etc.) affect the condition of the spark plug. These factors cause deposits to form on the insulator nose, which may degrade performance. Removing the Spark Plug N Shut off the engine. 1 2 N Remove the spark plug boot (1). N Unscrew the spark plug (2). WARNING If the cutting attachment continues to run when the engine is idling, have your machine checked and repaired by your servicing dealer. 0414BA015 KN FS 70 R 31