Service Manual — page 276 of 715

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5-26 ENGINE TOP END
Cylinder Head
Cylinder Compression Measurement
                             NOTE
  ○Use the battery which is fully charged.
• Warm  up the engine thoroughly.
• Remove: engine.
  Stop the
• Spark Plugs (see Spark Plug Replacement in the Peri-
   odic Maintenance chapter)

• Attach    the compression gauge [A] and adapter [B] firmly
  into the spark plug hole.
• Using   the starter motor, turn the engine over with the throt-
  tle fully open until the compression gauge stops rising; the
  compression is the highest reading obtainable.
  Special Tools - Compression Gauge, 20 kgf/cm²: 57001-221
                  Compression Gauge Adapter, M10 × 1.0:
                     57001-1601
                  L-Shape Hose: 57001-1606

  Cylinder Compression
    Usable Range:   770 ∼ 1 198 kPa (7.9 ∼ 12.2 kgf/cm²,
                    112 ∼ 174 psi) @236 r/min (rpm)

• Repeat   the measurement for the other cylinders.
• the Periodicspark
  Install the       plugs (see Spark Plug Replacement in
                Maintenance chapter).

○The following table should be consulted if the obtainable compression reading is not within the us-
  able range.
       Problem                       Diagnosis                              Remedy (Action)
Cylinder compression Carbon accumulation on piston and in           Remove the carbon deposits
is higher than usable combustion chamber possibly due to            and replace damaged parts if
range.                damaged valve stem oil seal and/or            necessary.
                      damaged piston oil rings (This may be
                      indicated by white exhaust smoke).
                      Incorrect cylinder head gasket                Replace the gasket with a standard
                      thickness                                     part.
Cylinder compression Gas leakage around cylinder head               Replace damaged gasket and
is lower than usable                                                check cylinder head warp.
range.                Bad condition of valve seating                Repair if necessary.
                      Incorrect valve clearance                     Adjust the valve clearance.
                      Incorrect piston/cylinder clearance           Replace the piston and/or cylinder.
                      Piston seizure                                Inspect the cylinder and
                                                                    replace/repair the cylinder and/or
                                                                    piston as necessary.
                          Bad condition of piston ring and/or       Replace the piston and/or the
                          piston ring grooves                       piston rings.