Yamaha XMAX YP125R - Service manual > Checking the spark plug cap

1. Check:

• Spark plug cap resistance

Out of specification → Replace.

Resistance 10.0 kΩ

a. Remove the spark plug cap from the spark plug lead.

b. Connect the pocket tester (Ω × 1k) to the spark plug cap as shown.

Pocket tester 90890-03112

Analog pocket tester YU-03112-C

c. Measure the spark plug cap resistance.

Checking the ignition coil

1. Check:

• Primary coil resistance

Out of specification → Replace.

Primary coil resistance 2.16-2.64 Ω at 20 ºC (68 ºF)

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

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

Pocket tester 90890-03112

Analog pocket tester YU-03112-C

• Positive tester probe → red/black "1"
• Negative tester probe → orange "2"

c. Measure the primary coil resistance.

2. Check:

• Secondary coil resistance

Out of specification → Replace.

Secondary coil resistance 8.64-12.96 kΩ at 20 ºC (68 ºF)

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

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

Pocket tester 90890-03112

Analog pocket tester YU-03112-C

• Positive tester probe → red/black "1"
• Negative tester probe → Spark plug lead "2"

c. Measure the secondary coil resistance.

Checking the ignition spark gap

1. Check:

• Ignition spark gap

Out of specification → Perform the ignition system troubleshooting, starting with step 5.

Minimum ignition spark gap 6.0 mm (0.24 in)

TIP

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.

Ignition checker 90890-06754

Oppama pet-4000 spark checker YM-34487

2. Spark plug cap

c. Set the main switch to "ON".

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 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 sensor/stator assembly.

Crankshaft position sensor resistance 248-372 Ω at 20 ºC (68 ºF)

a. Connect the pocket tester (Ω × 100) to the crankshaft position sensor coupler as shown.

Pocket tester 90890-03112

Analog pocket tester YU-03112-C

• Positive tester probe → red "1"
• Negative tester probe → white "2"

b. Measure the crankshaft position sensor resistance.

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