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    UF4D14E0.book  Page 64  Tuesday, March 27, 2018  1:02 PM

                                                                                 Maintenance

                            EJU3437B
                            Checking the spark plugs              TIP:
                            EWJ00351                              When the engine is operating normally, the
                                 WARNING                          color of the spark plug electrode portion will
                            Be careful not to damage  the  insulator  be a medium-to-light tan.
                            when removing or installing a spark plug.
                            A damaged insulator could allow sparks to
                            escape, which could result in a fire or ex-
                            plosion.

                            Remove and check the condition of the spark
                            plugs.
                            The condition of a  spark plug can indicate
                            something about the condition of the engine.
                            For example, if the center electrode portion is
                            very white, this could indicate an intake air  1 Insulator
                            leak or carburetion problem in that cylinder.  2 Electrode
                            Do  not attempt  to diagnose any  problems  3 Spark plug gap
                            yourself. Have a Yamaha dealer service the
                                                                    Specified spark plug:
                            watercraft.                               B7HS
                            To remove a spark plug:                 Spark plug gap:
                            (1) Remove the hood. (See page 27 for hood  0.6–0.7 mm (0.024–0.028 in)
                                removal and installation procedures.)
                            (2) Remove the spark plug cap.        To install a spark plug:
                            (3) Remove the spark plug, and then check  (1) Wipe off any dirt from the threads, insu-
                                the condition of the spark plug and the  lator,  and  gasket surface of the spark
                                spark plug gap. If the electrode portion is  plug.
                                significantly discolored, if electrode ero-  (2) Install the spark plug, and then tighten it
                                sion becomes excessive, if carbon and  to the specified torque.
                                other deposits are excessive,  or  if  the
                                                                    Tightening torque:
                                spark plug gap is not within the specified  Spark plug:
                                range, replace the spark plug.          25 N·m (2.5 kgf·m, 18 lb·ft)

                                                                  TIP:
                                                                  If a torque-wrench is not available when you
                                                                  are reinstalling a spark plug, a good estimate
                                                                  of the correct torque is 1/12 turn past finger-
                                                                  tight. When you  are  installing  a new spark
                                                                  plug, a good estimate of the correct torque is
                                                                  1/2 to 2/3 turn past finger-tight.
                                                                  (3) Wipe  off any water or dirt inside  the
                                                                     spark plug cap.

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