mxu 500 irs efi Manuale-dofficina : Pagina 147

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Pagina 145

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Pagina 146

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Pagina 148

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Pagina 149

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          8. CYLINDER HEAD/VALVES                                              MXU 500 IRS


 CYLINDER COMPRESSION TEST

 Warm up the engine to normal operating
 temperature.
 Stop the engine and remove the spark plug
 cap and remove the spark plug (refer to the
 "SPARK PLUG" section in the chapter 3).




                                                 Park Plug Cap




                                                 Compression Gauge
 Install a compression gauge into the spark
 plug hole.

 Open the throttle all the way and crank the
 engine with the starter motor until the gauge
 reading stops rising.
 The maximum reading is usually reached 4 ­
 7 seconds.
 To avoid discharging the battery, do not
   operate the starter motor for more than
   seven seconds.

 Compression pressure:
                15 kg/cm2 (1500 kPa, 213 psi)


 Low compression can be caused by:
  Blown cylinder head gasket
  Improper valve adjustment
  Valve leakage
  Worn piston ring or cylinder

 High compression can be caused by:
  Carbon deposits in combustion chamber or
  on piston head




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