4-11EEMU01202CLEANING AND ADJUSTING SPARKPLUGwWhen removing or installing a spark plug,be careful not to damage the insulator. Adamaged insulator could allow externalsparks, which could lead to explosion orfire.The spark plug is an important enginecomponent and is easy to inspect. Thecondition of the spark plug can indicatesomething about the condition of theengine. For example, if the center elec-trode porcelain is very white, this couldindicate an intake air leak or carburetionproblem in that cylinder. Do not attemptto diagnose any problems yourself.Instead, take the outboard motor to aYamaha dealer. You should periodicallyremove and inspect the spark plugbecause heat and deposits will cause thespark plug to slowly break down anderode. If electrode erosion becomesexcessive, or if carbon and other depositsare excessive, you should replace thespark plug with another of the correcttype.Before fitting the spark plug, measure theelectrode gap with a wire thicknessgauge; adjust the gap to specification ifnecessary.Standard spark plug:Refer to “SPECIFICATIONS”, page 4-1.Spark plug gap:Refer to “SPECIFICATIONS”, page 4-1.
