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 ...

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    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 ...

    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. ...

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    The drive chain consists of many interacting parts. If the drive chain is not maintained properly, it will wear out quickly. Therefore, the drive chain should be serviced, especially when the vehicle is used in dusty areas. This vehicle has a drive chain with small rubber O-rings between eac ...

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