Stihl HL 90 Product Instruction Manual - Page 21

English Spark Arresting Screen in Muffler The muffler is equipped with a spark arresting screen. N If the engine is down on power, check the spark arresting screen in the muffler. N Wait for the muffler to cool down. N Move the slide control to STOP-0. 1 N Take out the screw (1). 249BA059 KN N Take out the screw (4). N Lift the spark arresting screen (5) and pull it out. N Clean the spark arresting screen. If the screen is damaged or heavily carbonized, fit a new one. N Refit the spark arresting screen. N Insert screw and tighten it down firmly. N Install the shroud. Spark Plug If engine is down on power, difficult to start or runs poorly at idling speed, first check the spark plug. Fit a new spark plug after approx. 100 operating hours or earlier if the electrodes are badly eroded. 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 result in trouble in operation. Removing the spark plug N Move the slide control to STOP-0. 249BA063 KN 3 2 2 N Take out the screws (2) and remove the shroud (3). 249BA060 KN 1 N Pull off the spark plug boot (1). N Unscrew the spark plug. HL 90 K 19