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:
Assembling the oil pump
1. Lubricate:
Oil pump inner rotor
Oil pump outer rotor
Oil pump driven gear
(with the recommended lubricant)
2. Install:
Oil pump outer rotor
Oil pump inner rotor "1"
Oil pump driven gear
Pin "2"
NOTE:
When installing the inner rotor, align the pin "2"
in the oil pump sh ...
Checking the connections
Check the leads, couplers, and connectors for
stains, rust, moisture, etc.
1. Disconnect:
Lead
Coupler
Connector
2. Check:
Lead
Coupler
Connector
Moisture → Dry with an air blower.
Rust/stains → Connect and disconnect several
times.
3. Check:
All co ...
Adjusting the front wheel static balance
NOTE:
After replacing the tire, wheel or both, the front
wheel static balance should be adjusted.
Adjust the front wheel static balance with the
brake discs installed.
1. Remove:
Balancing weight(s)
2. Find:
Front wheel's heavy spot
NOTE:
Place the front wheel on a suitab ...