Yamaha YZF-R125 Service Manual: 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 is within specification, the ignition system circuit is operating normally.

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

b. Connect the ignition checker "1" as shown.


Checking the ignition spark gap


2. Spark plug cap

c. Set the main switch to "ON" and the engine stop switch to " ".


d. Measure the ignition spark gap "a".

e. Crank the engine by pushing the start switch " " and gradually increase the
spark gap until a misfire occurs.

    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 ...

    Checking the crankshaft position sensor
    1. Disconnect: Crankshaft position sensor coupler (from the wire harness) 2. Check: Crankshaft position sensor resistance Out of specification  Replace the crankshaft position senso ...

    Other materials:

    Checking the connections
    Check the leads, couplers, and connectors for stains, rust, moisture, etc. 1. Disconnect: Lead Coupler Connector 2. Check: Lead Coupler Connector Moisture → Dry with an air blower. Rust/stains → Connect and disconnect several times. 3. Check: All co ...

    Checking the coolant level
    1. Stand the vehicle on a level surface. NOTE: Place the vehicle on a suitable stand. Make sure the vehicle is upright. 2. Check: Coolant level The coolant level should be between the maximum level mark "a" and minimum level mark "b". Below the minimum level mark →  Add t ...

    Throttle position sensor
    1. Check: Throttle position sensor a. Connect the digital circuit tester to the terminals of the throttle body sensor assembly coupler as shown. Positive tester probe → gray/red terminal "1" Negative tester probe → gray/black terminal "2" b. Measure the throttle pos ...

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