Stihl KM 91 R Product Instruction Manual - Page 18

English Engine Management Adjusting the Carburetor Exhaust emissions are controlled by the design of the fundamental engine parameters and components (e.g. carburation, ignition, timing and valve or port timing) without the addition of any major hardware. The carburetor has been set at the factory to provide an optimum fuel-air mixture under most operating conditions. Adjusting Idle Speed Spark Arresting Screen in Muffler N If the engine is down on power, check the spark arresting screen in the muffler. N Wait for the muffler to cool down. 4 0000-GXX-0495-A0 0000-GXX-0486-A0 5 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 attachment must not run. Attachment runs when engine is idling N Turn the idle speed screw (LA) slowly counterclockwise until the cutting attachment stops running and then turn the screw about another 1/2 to 3/4 turn in the same direction. WARNING If the attachment continues to run when the engine is idling, have your machine checked and repaired by your servicing dealer. N Take out the screw (4). N Lift the spark arresting screen (5) and pull it out. N Clean the spark arresting screen (5). If the screen is damaged or heavily carbonized, install a new one. N Refit the spark arresting screen (5). N Insert the screw (4) and tighten it down firmly. 16 KM 91 R