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:

    Electrical components
    1. Main switch 2. Clutch switch 3. Front brake light switch 4. Ignition coil 5. Throttle body sensor assembly (intake air pressure sensor, intake air temperature sensor, throttle position sensor) 6. FID (fast idle solenoid) 7. Rectifier/regulator 8. Lean angle sensor 9. Starting circui ...

    Installing the camshaft and rocker arms
    1. Lubricate: Rocker arms Rocker arm shafts 2. Lubricate: Camshaft 3. Install: Camshaft "1" NOTE: Make sure that the camshaft projections "a" and hole "b" are positioned as shown in the illustration. 4. Install: Rocker arms Rocker arm shafts "1" NOTE: Make ...

    Disassembling the water pump
    1. Remove: Water pump seal "1" NOTE: Remove the water pump seal from the inside of the water pump housing "2". 2. Remove: Bearing "1" NOTE: Remove the bearing from the outside of the water pump housing "2". ...

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