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For exact service procedures for your model Suzuki outboard engine refer to your Service Manual.

For spark plug inspection times and replacement intervals (see maintenance chart).

Standard spark plug type: See engine specifications.

CAUTION: Type of spark plugs differ between year and model. Using improper spark plugs can not only cause engine damage but can cause ignition system malfunctions.


Inspect for a carbon deposit on the spark plug bases. If carbon is present, remove carbon with a spark plug cleaning machine or by carefully using a pointed tool.


Measure for the spark plug gap using the thickness gauge. Adjust to within the specified range if the gap is out of the specification.

Spark plug gap : (see specifications in Repair Manual).
Special tool required : A special tool is required to gauge the thickness on the spark plug gap.


Check the electrode and insulator condition. If the electrode is extremely worn or burnt, replace the spark plug. If the spark plug has a broken insulator, damaged threads, etc., replace the spark plug.

CAUTION: Confirm the thread size and reach when replacing the plug. If the reach is too short, carbon will be deposited on the threaded portion of the plug hole resulting in possible engine damage.

Tightening torque: For spark plug torque specs refer to tightening torque spec's.


Suzuki Models / Horsepower / Model Years

DF4 DF4 DF6 DF9.9 DF15 DF25 DF30 DF40 DF50 DF50 DF40QH DF50QH DF40T DF50T DF40Y DF50Y DF70 DF80 DF90 DF100 DF115 DF175 QH T Y 4HP 5HP 6HP 9.9HP 15HP 25HP 30HP 40HP 50HP 60HP 70HP 90HP 115HP 140HP 150HP 175HP 4 5 6 9.9 15 25 30 40 50 60 70 90 100 115 140 150 175 HP 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 99 00 01 02 03 04 05 06 07 08 09 10 11 Service Manual Repair Owner's Guide Diy Boat Engine Four Stroke 4-Stroke How To Fix.