Yamaha YZF-R125 Service Manual: Checking the ignition coil

1. Check:

Primary coil resistance Out of specification  Replace.


a. Disconnect the ignition coil connectors from the ignition coil terminals.

b. Connect the pocket tester ( × 1)
to the ignition coil as shown.


Positive tester probe
red/white "1"

Negative tester probe
orange "2"

Checking the ignition coil


c. Measure the primary coil resistance.

2. Check:

Secondary coil resistance Out of specification Replace.


 a. Disconnect the spark plug cap from the ignition coil.

b. Connect the pocket tester ( ×
1k) to the ignition coil as shown.


  • Positive tester probe
    orange "1"
  • Negative tester probe
    spark plug lead "2"

Checking the ignition coil


c. Measure the secondary coil resistance.

    Checking the spark plug cap
    1. Check: Spark plug cap resistance Out of specification Replace. a. Remove the spark plug cap from the spark plug lead. b. Connect the pocket tester ( × 1k) to the spark plug cap as ...

    Checking the ignition spark gap
    1. Check: Ignition spark gap Out of specification Perform the ignition system troubleshooting, starting with step 5. Refer to "TROUBLESHOOTING" on page 8-3. NOTE: If the ignition spark gap ...

    Other materials:

    Checking the shift shaft
    1. Check: Shift shaft Bends/damage/wear Replace. Shift shaft spring Damage/wear Replace. Checking the stopper lever 1. Check: Stopper lever Bends/damage Replace. Roller turns roughly Replace the stopper lever. Stopper lever spring Damage/wear Replace. ...

    Checking the cylinder and piston
    1. Check: Piston wall Cylinder wall Vertical scratches Replace the cylinder, and replace the piston and piston rings as a set. 2. Measure: Piston-to-cylinder clearance a. Measure cylinder bore "C" with the cylinder bore gauge. NOTE: Measure cylinder bore "C" by takin ...

    General tightening torque specifications
    This chart specifies tightening torques for standard fasteners with a standard ISO thread pitch. Tightening torque specifications for special components or assemblies are provided for each chapter of this manual. To avoid warpage, tighten multi-fastener assemblies in a crisscross pattern and ...

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