Yamaha YZF-R125 Service Manual: Checking the valve springs

The following procedure applies to all of the valve springs.

1. Measure:

  • Valve spring free length "a" Out of specification Replace the valve spring.

Checking the valve springs


2. Measure:

  • Compressed valve spring force "a" Out of specification Replace the valve spring.

Checking the valve springs


b. Installed length

3. Measure:

  • Valve spring tilt "a" Out of specification Replace the
    valve spring.

Checking the valve springs


    Checking the valve seats
    The following procedure applies to all of the valves and valve seats. 1. Eliminate: Carbon deposits (from the valve face and valve seat) 2. Check: Valve seat Pitting/wear Replace the ...

    Installing the valves
    The following procedure applies to all of the valves and related components. 1. Deburr: Valve stem end (with an oil stone) 2. Lubricate: Valve stem "1" Valve stem seal "2" (with ...

    Other materials:

    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 2. Check: Cylinder head Damage/scratches   Replace. Cylinder head water jacket Min ...

    Checking the brake fluid level
    Front brake Front brake Minimum level mark Rear brake Rear brake Minimum level mark Insufficient brake fluid may allow air to enter the brake system, possibly causing it to become ineffective. Before riding, check that the brake fluid is above the minimum level mark an ...

    Removing the front wheel (disc)
    1. Stand the vehicle on a level surface. WARNINGSecurely support the vehicle so that there is no danger of it falling over. 2. Elevate: Front wheel NOTE: Place the vehicle on a suitable stand so that the front wheel is elevated. 3. Remove: Front brake caliper NO ...

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