Yamaha YZF-R125 Service Manual: Checking the camshaft sprocket and timing chain guide

Yamaha YZF-R125 Service Manual / Engine / Cylinder head / Checking the camshaft sprocket and timing chain guide

1. Check:

  • Camshaft sprocket More than 1/4 tooth wear "a" Replace
    the camshaft sprocket, timing chain and crankshaft as a set.

Checking the camshaft sprocket and timing chain guide


a. 1/4 tooth

b. Correct

1. Timing chain roller

2. Camshaft sprocket

2. Check:

Timing chain guide (exhaust side) Damage/wear Replace.


    Checking the cylinder head
    1. Eliminate: Combustion chamber carbon deposits (with a rounded scraper) NOTE: Do not use a sharp instrument to avoid damaging or scratching: Spark plug bore threads Valve seats ...

    Checking the timing chain tensioner
    1. Check: Timing chain tensioner Cracks/damage/rough movement Replace. a. Lightly press the timing chain tensioner rod into the timing chain tensioner housing by hand. NOTE: While pressing the ...

    Other materials:

    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 ...

    Checking the front brake hose
    1. Check: Brake hose "1" Cracks/damage/wear  Replace. 2. Check: Brake hose holder "2" Loose connection Tighten the holder bolt. 3. Hold the vehicle upright and apply the front brake several times. 4. Check: Brake hose Brake fluid leakage Replace the da ...

    Troubleshooting
    The starter motor fails to turn. NOTE: Before troubleshooting, remove the following part(s): 1. Seats 2. Fuel tank 3. Left lower side cowling 4. Left upper side cowling ...

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