Yamaha YZF-R125 Service Manual: Checking the decompression system

Yamaha YZF-R125 Service Manual / Engine / Cylinder head / 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" moves smoothly.

c. Without operating the decompression lever, check that the decompression cam "2" projects from the camshaft (exhaust cam) as shown in the illustration "A".

d. Move the decompression lever "1" in the direction of the arrow shown and check that the decompression cam does not project from the camshaft (exhaust cam) as shown in the illustration "B".

Checking the decompression system


Checking the decompression system


    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 ...

    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 ...

    Other materials:

    Preparation for removal and disassembly
    1. Before removal and disassembly, remove all dirt, mud, dust and foreign material. 2. Use only the proper tools and cleaning equipment. Refer to "SPECIAL TOOLS" on page 1-8. 3. When disassembling, always keep mated parts together. This includes gears, cylinders, pistons and other part ...

    Checking the timing chain and timing chain guide
    1. Check: Timing chain Damage/stiffness Replace the timing chain and camshaft sprocket as a set. 2. Check: Timing chain guide (intake side) Damage/wear Replace. Checking the oil strainer 1. Check: Oil strainer Damage   Replace. Contaminants Clean with solvent. ...

    Installing the radiator
    1. Fill: Cooling system (with the specified amount of the recommended coolant) Refer to "CHANGING THE COOLANT" on page 3-15. 2. Check: Cooling system Leaks Repair or replace any faulty part. 3. Measure: Radiator cap opening pressure Below the specified pressure Repla ...

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