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:

    Main switch/steering lock
    Main switch/steering lock The main switch/steering lock controls the ignition and lighting systems, and is used to lock the steering. The various positions are described below. ON All electrical circuits are supplied with power, the meter lighting, taillight, license plate light and ...

    Installing the valves
    The following procedure applies to all of the valves and related components. 1. Deburr: Valve stem end (with an oil stone) 2. Lubricate: Valve stem "1" Valve stem seal "2" (with the recommended lubricant) 3. Install: Lower spring seat "1" Valve stem seal "2" V ...

    Removing the rear brake master cylinder
    NOTE: Before removing the rear brake master cylinder, drain the brake fluid from the entire brake system. 1. Disconnect: Rear brake light switch coupler 2. Loosen: Rear brake light switch "1" 3. Remove: Rear brake master cylinder bolts Rear brake master cylinder 4. Remove: ...

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