Adjusting a carburetor usually needs 5 steps:
Step 1: Remove the air filter cover and insert a screwdriver through the opening in the air filter base.
Step 2: Back the idle speed screws out until it does not contact the carburetor throttle lever. Then turn the screw in until it just begins to move the throttle lever; then continue turning for 2 more full turns.
Step 3: Insert a small flat-blade screwdriver through the hole at the back of the top handle. Turn the high-speed and idle-speed mixture needles out until the limiter caps stop.
Step 4: Start the engine and let it run for a minute.
Step 5: Release the throttle trigger and let the engine idle.