Yamaha YZF-R125 Service Manual: Poor medium-and-high-speed performance
Refer to "STARTING FAILURES" on page 9-1.
Engine
1. Air filter
- Clogged air filter element
Fuel system
1. Fuel pump
- Faulty fuel pump
Faulty gear shifting
Shifting is difficult
Refer to "Clutch drags".
Incorrect engine idling speed
Engine
1. Cylinder and cylinder head
Incorrect valve clearance
Damaged valve train components
2. Air filter
Clogged air filter element
Fuel system
1. Throttle body
Damaged or loo ...
Shift pedal does not move
Shift shaft
Improperly adjusted shift rod
Bent shift shaft
Shift drum and shift forks
Foreign object in a shift drum groove
Seized shift fork
Bent shift fork guide bar
Transmission ...
Other materials:
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 ...
Checking the cooling system
1. Remove:
Side covers
Upper side cowlings
Refer to "GENERAL CHASSIS" on page 4-1.
2. Check:
Radiator "1"
Radiator inlet hose "2"
Radiator outlet hose "3"
Coolant reservoir hose "4"
Water pump breather hose "5"
Cracks/damage → Replace.
Refer to "RADIATOR" on page 6-1 ...
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 ...