Stihl 009 Instruction Manual - Page 41

Exhaust emissions are controlled by the design of the fundamental engine parameters and components (e.g. carburetion, ignition, timing and valve or port timing) without the addition of any major hardware. It is usually necessary to change the setting of the idle speed adjusting screw after every correction to the low speed screw . • Turn the idle speed adjusting screw clockwise until chain begins to run then back off the screw one quarter of a turn. • Check the air filter and clean it if necessary. • Warm up the engine. • Turn screws only very slightly and carefully - even minor changes have a noticeable effect on the engine's running behavior. • Turn the idle speed adjusting screw counterclockwise until chain stops running then turn screw another quarter turn in the same direction. •Idle setting is too lean. Turn the low speed adjusting screw counterclockwise until engine runs and accelerates smoothly.