kpw 50 Workshop-manual : Page 30

          2. INSPECTION/ADJUSTMENT                                             NEXXON 50

  IGNITION TIMING
  The CDI unit is not adjustable.
    If the ignition timing is incorrect, check
    the ignition system.

  Remove the ignition timing eye hole cap on
  the left crankcase cover.



                                                     Eye Hole

  Check the ignition timing with a timing light.
  When the engine is running at idle speed, the
  ignition timing is correct if the index mark
  on the left crankcase cover aligns with the
  "F" mark on the flywheel.




                                                   Timing Light
                                                          "F" Mark
  CYLINDER COMPRESSION
  Warm up the engine before compression test.
  Stop the engine, then remove the spark plug
  and insert a compression gauge.
  Open the throttle valve fully and crank the
  engine with the starter motor or kick lever.
  Measure the compression.
  Compression: 13     2kg/cm




                                                                     Compression Gauge
  If the compression is low, check for the
  following:
  Leaky valves
  Valve clearance to small
  Leaking cylinder head gasket
  Worn piston rings
  Worn piston/cylinder
  If the compression is high, it indicates that
  carbon deposits have accumulated on the
  combustion chamber and the piston head.




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