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Page 71 - LIT-18626-12-56
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    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 26 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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