Yamaha YZF-R125 Service Manual: Checking the camshaft sprocket and timing chain guide

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

Checking the camshaft sprocket and timing chain guide


a. 1/4 tooth

b. Correct

1. Timing chain roller

2. Camshaft sprocket

2. Check:

Timing chain guide (exhaust side) Damage/wear Replace.


    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 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 ...

    Other materials:

    Air induction system
    1. Air induction system hose (air filter case to reed valve assembly) 2. Air induction system reed valve assembly 3. Air induction system hose (reed valve assembly to exhaust pipe) Checking the air induction system Air injection The air induction system burns unburned exhaust gases b ...

    Checking the radiator fan motor
    1. Check: Radiator fan motor Faulty/rough movement → Replace. a. Disconnect the radiator fan motor coupler from the wire harness. b. Connect the battery (DC 12 V) as shown. Positive tester probe → blue "1" Negative tester probe → black "2" c. Measure ...

    Disassembling the rear brake caliper
    1. Remove: Brake caliper piston "1" Brake caliper piston dust seal "2" Brake caliper piston seal "3" a. Blow compressed air into the brake hose joint opening "a" to force out the piston from the brake caliper. WARNING Cover the brake caliper piston with a rag. Be careful no ...

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