Yamaha YZF-R125 Service Manual: Removing the piston

Removing the piston


1. Remove:

  • Piston pin clips "1"

  • Piston pin "2"

  • Piston "3"

CAUTION:

Do not use a hammer to drive the piston pin out.

NOTE:

  • Before removing the piston pin clip, cover the crankcase opening with a clean rag to prevent the piston pin clip from falling into the crankcase.

  • Before removing the piston pin, deburr the piston pin clip groove and the piston pin bore area.

    If both areas are deburred and the piston pin is still difficult to remove, remove it with the piston pin puller set "4".


Removing the piston


2. Remove:

  • Top ring

  • 2nd ring

  • Oil ring

NOTE:

When removing a piston ring, open the end gap with your fingers and lift the other side of the ring over the piston crown.

Removing the piston


    Cylinder and piston
    ...

    Checking the cylinder and piston
    1. Check: Piston wall Cylinder wall Vertical scratches Replace the cylinder, and replace the piston and piston rings as a set. 2. Measure: Piston-to-cylinder clearance a. Mea ...

    Other materials:

    Checking the fuel line
    1. Remove: Left side panel Refer to "GENERAL CHASSIS" on page 4-1. 2. Lift the fuel tank. (Do not disconnect the fuel hose, drain hose 3. Check: Fuel hose "1" Cracks/damage → Replace. Loose connection Connect properly. 4. Install: Fuel tank Refer to "FUEL TANK" on pa ...

    Installing the water pump
    1. Install: Water pump assembly "1" O-rings "2" NOTE: Align the projection "a" on the impeller shaft with the slit "b" on the camshaft sprocket bolt. Lubricate the O-rings with a thin coat of lithiumsoap- based grease. 2. Fill: Cooling system (with the specified amou ...

    Intake air pressure sensor
    1. Check: Intake air pressure sensor output voltage Out of specification Replace the throttle body. a. Connect the pocket tester (DC 20 V) to the throttle body sensor assembly coupler as shown. Positive tester probe pink/white "1" Negative tester probe gray/black "2" ...

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