Stihl HS 87 Instruction Manual - Page 25

2 N Remove the exhaust pipe (2). 3 N Use a 16 mm socket wrench to unscrew the spark arresting screen (3). 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 Fit the exhaust pipe. N Fit the screws. 0000-GXX-6548-A0 0000-GXX-6547-A0 Spark Plug 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 Pull off the spark plug boot. N Unscrew the spark plug. 0023BA025 KN Checking the spark plug English 000BA039 KN A N Clean the spark plug if it is dirty N Check the electrode gap (A) and readjust if necessary - see "Specifications" N Use only resistor type spark plugs of the approved range. See the chapter "Specifications" in this instruction manual Correct the problems that have caused fouling of the spark plug: - too much oil in fuel mix; - dirty air filter; or - unfavorable running conditions, e.g. operating at part throttle. HS 87 R, HS 87 T 23