Yamaha YZF-R125 Service Manual: Checking the rocker arms and rocker arm shafts

Yamaha YZF-R125 Service Manual / Engine / Camshaft / Checking the rocker arms and rocker arm shafts

The following procedure applies to all of the rocker arms and rocker arm shafts.

1. Check:

  • Rocker arm Damage/wear Replace.

2. Check:

  • Rocker arm shaft Blue discoloration/excessive wear/pitting/ scratches  Replace or
    check the lubrication system.

3. Measure:

  • Rocker arm inside diameter "a" Out of specification Replace.

Checking the rocker arms and rocker arm shafts


4. Measure:

  • Rocker arm shaft outside diameter "a" Out of specification Replace.

Checking the rocker arms and rocker arm shafts


5. Calculate:

  • Rocker-arm-to-rocker-arm-shaft clearance

NOTE:

Calculate the clearance by subtracting the rocker arm shaft outside diameter from the rocker arm inside diameter.

Out of specification Replace the
defective part(s).


    Checking the camshaft
    1. Check: Camshaft lobes Blue discoloration/pitting/scratches  Replace the camshaft. 2. Measure: Camshaft lobe dimensions "a" and "b" Out of specification Replace the cams ...

    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 s ...

    Other materials:

    Checking the turn signal relay
    1. Check: Turn signal relay input voltage Out of specification →The wiring circuit from the main switch to the turn signal relay coupler is faulty and must be repaired. a. Connect the pocket tester (DC 20 V) to the turn signal relay terminal as shown. - Positive tester probe  b ...

    Checking the timing chain and timing chain guide
    1. Check: Timing chain Damage/stiffness Replace the timing chain and camshaft sprocket as a set. 2. Check: Timing chain guide (intake side) Damage/wear Replace. Checking the oil strainer 1. Check: Oil strainer Damage   Replace. Contaminants Clean with solvent. ...

    Checking the stator coil
    1. Disconnect: Stator coil coupler (from the wire harness) 2. Check: Stator coil resistance Out of specification → Replace the crankshaft position sensor/stator assembly. a. Connect the pocket tester ( × 1) to the stator coil coupler as shown. b. Measure the sta ...

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