Prior to Adjusting the Carburetor

• 1). Unscrew the cover to the air filter with your hand or depress the tabs on the side of the air filter cover. Remove it from the engine. Lift the air filter off its engine seat.
  
  
• 2). Separate the filter from its outer shell. Clean the air filter with two-cycle fuel. Pour about a spoonful over the filter. Rub it in and wipe it off with the rag. Slap the filter against a hard, clean surface, like your palm, to remove any excessive fuel. Reinstall the air filter.
  
  
• 3). Remove any old or bad gas from the fuel tank. Pour its contents into an approved fuel container. Fill the fuel tank with freshly mixed two-cycle fuel.
  
  
• 4). Start the engine and run it at a high idle for several minutes to warm it up.
  
  

Adjusting the Carburetor

• 1). Locate the carburetor adjustment screws. On most Stihl products, these screws are on the side of the air filter cover and may be marked with an "H," "L" or an "I."
  
  
• 2). Insert the small screwdriver into the screw marked with an "I" or an "L." Turn the screw in clockwise, 1/8 of a turn, to reduce the amount of fuel in the carburetor. Continue turning the screw at 1/8 increments until the engine idles smoothly.
  
  
• 3). Turn the screw counterclockwise in 1/8 increments to decrease the idle speed. Use 1/8 turns until the chain or head stops spinning and the engine idles smoothly.