Yamaha YZF-R125 Service Manual: Checking the spark plug

1. Remove:

  • Right side cover Refer to "GENERAL CHASSIS" on page 4-1.

2. Disconnect:

  • Spark plug cap

3. Remove:

  • Spark plug
CAUTION:

Before removing the spark plug, blow away any dirt accumulated in the spark plug well with compressed air to prevent it from falling into the cylinder.

4. Check:

Spark plug type Incorrect →Change.


5. Check:

  • Electrode "1" Damage/wear→ Replace the spark plug.
  • Insulator "2" Abnormal color→ Replace the spark plug.

    Normal color is medium-to-light tan.

6. Clean:

  • Spark plug (with a spark plug cleaner or wire brush)

7. Measure:

  • Spark plug gap "a" (with a wire thickness gauge) Out of specification → Regap.

Checking the spark plug


8. Install:

  • Spark plug

NOTE:

Before installing the spark plug, clean the spark plug and gasket surface.

9. Connect:

  • Spark plug cap

10.Install:

  • Right side cover Refer to "GENERAL CHASSIS" on page 4-1.
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