Yamaha YZF-R125 Service Manual: Installing the cylinder head

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

1. Install:

  • Cylinder head

NOTE:

Pass the timing chain through the timing chain cavity.

2. Tighten:

  • Cylinder head bolts "1"

  • Cylinder head bolts "2"

NOTE:

  • Lubricate the cylinder head bolts and washers with engine oil.
  • Tighten the cylinder head bolts in the proper tightening sequence as shown and torque them in two stages.

Installing the cylinder head


3. Install:

  • Camshaft sprocket

a. Turn the crankshaft counterclockwise.

b. Align the "I" mark "a" on the generator rotor with the stationary pointer "b" on the generator cover.

c. Align the "I" mark "c" on the camshaft sprocket with the stationary pointer "d" on the cylinder head.

d. Install the timing chain onto the camshaft sprocket, and then install the camshaft sprocket onto the camshaft.

Installing the cylinder head


NOTE:

When installing the camshaft sprocket, be sure to keep the timing chain as tight as possible on the exhaust side.

CAUTION:

Do not turn the crankshaft when installing the camshaft(s) to avoid damage or improper valve timing.

e. While holding the camshaft, temporarily tighten the camshaft sprocket bolt.

f. Remove the wire from the timing chain.

4. Install:

  • Timing chain tensioner gasket

  • Timing chain tensioner

a. Apply sealant to the timing chain tensioner bolt threads.


b. While lightly pressing the timing chain tensioner rod by hand, turn the tensioner rod fully clockwise with a thin screwdriver "1".

c. With the timing chain tensioner rod turned all the way into the timing chain tensioner housing (with the thin screwdriver still installed), install the gasket and the timing chain tensioner "2" onto the cylinder block.

d. Tighten the timing chain tensioner bolts "3" to the specified torque.


Installing the cylinder head


e. Remove the screwdriver, make sure the timing chain tensioner rod releases.

5. Turn:

  • Crankshaft (several turns counterclockwise)

6. Check:

  • "I" mark "a" Align the "I" mark on the generator rotor with the stationary pointer "b" on the generator cover.
  • "I" mark "c" Align the "I" mark on the camshaft sprocket with the stationary pointer "d" on the cylinder head.

    Out of alignment Correct.


    Refer to the installation steps above.

Installing the cylinder head


7. Tighten:

  • Camshaft sprocket bolt

CAUTION:

Be sure to tighten the camshaft sprocket bolt to the specified torque to avoid the possibility of the bolt coming loose and damaging the engine.

8. Measure:

Valve clearance Out of specification Adjust.


Refer to "ADJUSTING THE VALVE CLEARANCE" on page 3-3.

    Checking the decompression system
    1. Check: Decompression system a. Check the decompression system with the camshaft sprocket and the decompression cam installed to the camshaft. b. Check that the decompression lever "1" ...

    Camshaft
    ...

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