How to Set the Idle on a Johnson Outboard

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Johnson outboard motors are used on a number of different powerboats, both by casual boaters and professionals. Over time, the carburetor may cause the idle speed of the engine to fall outside the suggested range. In this case, the idle will have to be adjusted manually to ensure that your boat continues to operate safely and within the given specifications.

Items you will need

  • Tachometer

  • Flat-head screwdriver

Start the boat's ignition.

Locate the spark plug lead underneath the panel near the ignition. Attach the tachometer to the lead.

Wait for the Johnson outboard to automatically drop into low idle. The engine will make noticeably less noise when this happens.

Observe the tachometer reading. Check your owner's manual for your model's recommended idle speed.

Shut off the engine.

Locate the pilot screw near the bottom of the carburetor. Turn it until it is loosely fitted in place.

Turn the screw 1 1/8 turns counterclockwise.

Start the ignition. Observe the tachometer reading.

Turn the screw clockwise to increase speed, counterclockwise to decrease speed. Adjust the speed until it falls into the recommended range for your model.


About the Author

Michael Larkin has been writing since 2005. He has worked as a photojournalist for CBS affiliates in Spokane, Washington, and Boise, Idaho. He has also freelanced for ESPN and PBS. Larkin currently writes a wide range of material, including corporate newsletters, blogs and ad copy, as well as the occasional magazine article. Larkin holds a Bachelor of Arts in journalism/mass communication from Whitworth College.

Photo Credits

  • motorboats for rent image by Ivonne Wierink from