How to Adjust Pilot Screws on an Outboard Motor

When the engine of your outboard motor sounds rough while idling, you need to adjust the pilot screws on the carburetor to balance the idle speed. Rough idling can be caused by the oil-to-gas fuel mixture or by the normal operation of the engine or motor over time. The pilot screws on an outboard motor can be adjusted to increase or decrease the idle speed of the motor with a screwdriver.

Things You'll Need

• Screwdriver

Instructions

1. Turn off the outboard motor.

2. Release the clips that secure the motor cover and remove the cover.

3. Locate the carburetor for the outboard engine. The pilot screws will be on the lower part of the carburetor.

4. Insert a screwdriver into the end of the pilot screw.

5. Turn the screw clockwise until it is all the way in then make 1 ½ outward turns to the screw.

6. Start the outboard engine and let it idle.

7. Turn the pilot screw counterclockwise or clockwise to make adjustments. Adjust the screw ¼ of a turn at a time until you find a suitable idle speed.

Tips & Warnings

• The normal RPM range for an outboard motor, when idling, is about 900 RPM.

• If you adjust the idle screws too much, to decrease the idle speed, you can stall the motor.

References

• Manhattan Yacht Club: Explanation of Outboard Engine Maintenance Tasks

Resources

• OutboardRepairs: 1985 Johnson 9.9 Idle Speed Adjustment
• HondaMarine: Owner's Manuals