Yamaha YZF-R125 Service Manual: Overheating

Yamaha YZF-R125 Service Manual / Troubleshooting / Overheating

Engine

1. Clogged coolant passages

Cylinder head and piston
Heavy carbon buildup

2. Engine oil

Incorrect oil level
Incorrect oil viscosity
Inferior oil quality

Cooling system

1. Coolant

Low coolant level

2. Radiator

Damaged or leaking radiator
Faulty radiator cap
Bent or damaged radiator fin

3. Water pump

Damaged or faulty water pump
Thermostat
Thermostat stays closed
Hose(s) and pipe(s)
Damaged hose
Improperly connected hose
Damaged pipe
Improperly connected pipe

Fuel system

1. Throttle body

Damaged or loose throttle body joint

2. Air filter

Clogged air filter element

Chassis

1. Brake(s)

Dragging brake

Electrical system

1. Spark plug

Incorrect spark plug gap
Incorrect spark plug heat range

2. Ignition system

Faulty ECU

Overcooling

Cooling system

1. Thermostat

Thermostat stays open

Faulty clutch

Clutch slips 1. Clutch Improperly assembled clutch Improperly adjusted clutch cable Loose or fatigued clutch spring Worn friction plate Worn clutch plate 2. Engine oil Incorrect oi ...

Poor braking performance

- Worn brake pad - Worn brake disc - Air in hydraulic brake system - Leaking brake fluid - Faulty brake caliper kit - Faulty brake caliper seal - Loose union bolt - Damaged brake hose - Oil or ...

Other materials:

Checking the transmission
1. Measure: Main axle runout (with a centering device and dial gauge "1") Out of specification Replace the main axle. 2. Measure: Drive axle runout (with a centering device and dial gauge "1") Out of specification Replace the drive axle. 3. Check: Transmiss ...

Installing the swingarm
1. Lubricate: Bearings Spacers Dust covers Pivot shaft 2. Install: Bearings "1" 2. Swingarm A. Left side B. Right side 3. Install: Swingarm adjusting collar "1" Swingarm "2" Pivot shaft Pivot shaft nut "3" a. Install, and then fully turn in the swingarm adju ...

Cleaning the air filter element
NOTE: There is a check hose "1" at the bottom of the air filter case. If dust and/or water collects in this hose, clean the air filter element and air filter case. 1. Remove: Rider seat Refer to "GENERAL CHASSIS" on page 4-1. 2. Remove: Fuel tank Refer to "FUEL TANK" on page ...