Yamaha YZF-R125 Service Manual: Adjusting the valve clearance
The following procedure applies to all of the valves.
NOTE:
- Valve clearance adjustment should be made on a cold engine, at room temperature.
- When the valve clearance is to be measured or adjusted, the piston must be at top dead center (TDC) on the compression stroke.
1. Remove:
- Bottom cowling Refer to "GENERAL CHASSIS" on page 4-1.
- Fuel tank Refer to "FUEL TANK" on page 7-1.
2. Disconnect:
- Spark plug cap
3. Remove:
- Spark plug
- Ignition coil "1"
- Plastic locking tie "2"
4. Disconnect:
- Main switch coupler "3"
- Left handlebar switch couplers "4"
- Cylinder head cover
- Cylinder head cover gasket Refer to "CYLINDER HEAD" on page 5-7.
NOTE:
When removing the cylinder head cover, lift it out from between the frame tubes.
5. Remove:
- Timing mark accessing screw "1"
- Crankshaft end accessing screw "2"
6. Measure:
- Valve clearance
Out of specification → Adjust.
a. Turn the crankshaft counterclockwise.
b. Align the TDC mark "a" on the generator rotor with the stationary pointer "b" on the generator cover.
c. Check that the cam lobes are positioned as shown in the illustration.
d. Measure the valve clearance with a thickness gauge "1".
Out of specification → Adjust.
7. Adjust: - Valve clearance
a. Loosen the locknut "1".
b. Insert a thickness gauge "2" between the end of the adjusting screw and the valve tip.
c. Turn the adjusting screw "3" in direction "a" or "b" until the specified valve clearance is obtained.
- Hold the adjusting screw to prevent it from
moving and tighten the locknut to specification.
d. Measure the valve clearance again.
e. If the valve clearance is still out of specification, repeat all of the valve clearance adjustment steps until the specified clearance is obtained.
8. Install:
- Crankshaft end accessing screw (along with the O-ring
) - Timing mark accessing screw
(along with the O-ring
)
9. Install:
- Cylinder head cover gasket
- Cylinder head cover
- Spark plug Refer to "CYLINDER HEAD" on page 5-7.
10.Connect:
- Left handlebar switch couplers "1"
- Main switch coupler "2"
11.Install:
- Plastic locking tie "3"
NOTE:
Fasten the wire harness (to horn), wire harness (to left handlebar switch), front brake light switch lead, right handlebar switch lead, and main switch lead to the frame with a plastic locking tie.
Refer to "CABLE ROUTING" on page 2-33.
12.Install:
- Ignition coil "4"
- Spark plug
13.Connect:
- Spark plug cap
14.Install:
- Fuel tank Refer to "FUEL TANK" on page 7-1.
- Bottom cowling Refer to "GENERAL CHASSIS" on page 4-1.
Engine
...
Adjusting the exhaust gas volume
NOTE:
Be sure to set the CO density level to standard,
and then adjust the exhaust gas volume.
1. Remove:
Rider seat
Refer to "GENERAL CHASSIS" on page 4-1.
2. Set the main switch to "OFF" ...
Other materials:
Checking the bulbs and bulb sockets
NOTE:
Do not check any of the lights that use LEDs.
Check each bulb and bulb socket for damage or
wear, proper connections, and also for continuity
between the terminals.
Damage/wear Repair or replace
the bulb,
bulb socket or both.
Improperly connected Properly
connect.
No c ...
Checking the coolant temperature sensor
1. Remove:
Coolant temperature sensor
WARNING
Handle the coolant temperature sensor
with special care.
Never subject the coolant temperature sensor
to strong shocks. If the coolant temperature
sensor is dropped, replace it.
2. Check:
Coolant temper ...
Removing the cylinder head
1. Align:
"I" mark "a" on the generator rotor
(with the stationary pointer "b" on the generator
cover)
a. Turn the crankshaft counterclockwise.
b. When the piston is at TDC on the compression
stroke, align the "I" mark "c" on the camshaft
sprocket with the mark "d" on the
cylinder h ...