Yamaha YZF-R125 Service Manual: Checking the cylinder head

Yamaha YZF-R125 Service Manual / Engine / Cylinder head / 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 cylinder head


2. Check:

  • Cylinder head Damage/scratches   Replace.

  • Cylinder head water jacket Mineral deposits/rust
    Eliminate.

3. Measure:

  • Cylinder head warpage Out of specification Resurface
    the cylinder head.

a. Place a straightedge "1" and a thickness gauge "2" across the cylinder head.

Checking the cylinder head


b. Measure the warpage.

c. If the limit is exceeded, resurface the cylinder head as follows.

d. Place a 400-600 grit wet sandpaper on the surface plate and resurface the cylinder head using a figure-eight sanding pattern.

NOTE:

To ensure an even surface, rotate the cylinder head several times.

    Removing the cylinder head
    1. Align: "I" mark "a" on the generator rotor (with the stationary pointer "b" on the generator cover) a. Turn the crankshaft counterclockwise. b. When the piston is at TDC on the compre ...

    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. a. 1/4 tooth b. Correct 1. Timing chain roller 2. C ...

    Other materials:

    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. a. 1/4 tooth b. Correct 1. Timing chain roller 2. Camshaft sprocket 2. Check: Timing chain guide (exhaust side) Damage/wear Replace. ...

    Shifting
    Shifting Shift pedal Neutral position Shifting gears lets you control the amount of engine power available for starting off, accelerating, climbing hills, etc. The gear positions are shown in the illustration. TIP To shift the transmission into the neutral position, press the ...

    Starting circuit cut-off system operation
    If the engine stop switch is set to " " and the main switch is set to "ON" (both switches are closed), the starter motor can only operate if at least one of the following conditions is met: The transmission is in neutral (the neutral switch is closed). The clutch lever is pulled to the ...

    2025 Copyright www.yam-r125.net |