Yamaha YZF-R125 Service Manual: Unstable handling

Yamaha YZF-R125 Service Manual / Troubleshooting / 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:

Installing the rear shock absorber assembly
1. Install: Rear shock absorber assembly Relay arm "1" NOTE: Install the relay arm as shown in the illustration. 2. Tighten: Rear shock absorber assembly upper nut Relay arm nut Rear shock absorber assembly lower nut 3. Install: Connecting arms NOTE: When ins ...

Checking and replacing the rear wheel sprocket
1. Check: Rear wheel sprocket More than 1/4 tooth "a" wear Replace the rear wheel sprocket. Bent teeth Replace the rear wheel sprocket. b. Correct 1. Drive chain roller 2. Rear wheel sprocket 2. Replace: Rear wheel sprocket a. Remove the self-locking nuts and the ...

Installing the rear wheel (disc)
1. Install: Rear brake disc NOTE: Tighten the brake disc bolts in stages and in a crisscross pattern. 2. Check: Rear brake disc Refer to "CHECKING THE REAR BRAKE DISC" on page 4-33. 3. Lubricate: Rear wheel axle Contact surface of rear wheel hub and rear wheel Whee ...