The Bolens weed eaters can be adjusted to always maintain the optimum idle speed. Adjusting this screw regularly will help maintain the best performance from your Bolens lawn trimmer. This screw opens and closes a vent inside the carburetor, which increases or decreases gas flow and the speed of the idle. Improper adjustment of the carburetor can cause serious, even permanent, engine damage. Don't attempt to adjust the carburetor with bad or old gas, or with a dirty air filter.
Unscrew the Bolens gas tank cap. Lift the engine on its side and pour out all the remaining fuel left in the tank if it's older than 72 hours. Fill the Bolens fuel tank with freshly mixed trimmer fuel.
Unscrew the air filter/muffler cover on the back of the Bolens engine. Take the cover off and pull out the circular air filter pad. Wash the air filter in the detergent and warm water.
Rinse under cool water. Squeeze all excess water and let it stand to dry thoroughly for several hours. Coat the outside of the pad with SAE 30 oil using a light coat when the pad has dried compeletly. Put the filter back in and fit the air filter/muffler cover on top.
Start the Bolens engine. Squeeze the throttle and let it warm up for several minutes. Find the carburetor adjusting screw hole on the top of the air filter/muffler cover. Hold the engine off the ground and insert the screw into the hole.
Turn the screw slowly clockwise until the cutting head begins to move without the trigger being squeezed. Turn the screw out counterclockwise slowly until the head stops moving. Move the screw in between these two points to locate the maximum idle speed before the cutting head starts to move.