Yamaha YZF-R125 Service Manual: Unstable handling

Handlebars

- Bent or improperly installed right handlebar

- Bent or improperly installed left handlebar

1. Steering head components

- Improperly installed upper bracket

- Improperly installed lower bracket (improperly tightened ring nut)

- Bent steering stem

- Damaged ball bearing or bearing race

2. Front fork leg(s)

- Uneven oil levels (both front fork legs)

- Unevenly tensioned fork spring (both front fork legs)

- Broken fork spring

- Bent or damaged inner tube

- Bent or damaged outer tube

3. Swingarm

- Worn bearing

- Bent or damaged swingarm

Rear shock absorber assembly

- Faulty rear shock absorber spring

- Leaking oil

Tire(s)

- Uneven tire pressures (front and rear)

- Incorrect tire pressure

- Uneven tire wear

Wheel(s)

- Incorrect wheel balance

- Deformed cast wheel

- Damaged wheel bearing

- Bent or loose wheel axle

- Excessive wheel runout

Frame

- Bent frame

- Damaged steering head pipe

- Improperly installed bearing race

    Faulty front fork legs
    Leaking oil - Bent, damaged or rusty inner tube - Cracked or damaged outer tube - Improperly installed oil seal - Damaged oil seal lip - Incorrect oil level (high) - Loose damper rod assembly bo ...

    Faulty lighting or signaling system
    Headlight does not come on - Wrong headlight bulb - Too many electrical accessories - Hard charging - Incorrect connection - Improperly grounded circuit - Poor contacts (main or light switch) - ...

    Other materials:

    Checking the cylinder head breather hose
    1. Remove: Left side panel Refer to "GENERAL CHASSIS" on page 4-1. 2. Check: Cylinder head breather hose "1" Cracks/damage → Replace. Loose connection → Connect properly. CAUTION:Make sure the cylinder head breather hose is routed correctly. ...

    Checking and lubricating the brake and clutch levers
    Brake lever Brake lever Clutch lever Clutch lever The operation of the brake and clutch levers should be checked before each ride, and the lever pivots should be lubricated if necessary. Recommended lubricants:Brake lever: Silicone grease Clutch lever: Lithium-soap ...

    Checking the ignition coil
    1. Check: Primary coil resistance Out of specification  Replace. a. Disconnect the ignition coil connectors from the ignition coil terminals. b. Connect the pocket tester ( × 1) to the ignition coil as shown. Positive tester probe red/white "1" Negative tester probe orange ...

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