Yamaha YZF-R125 Service Manual: Intake air pressure sensor
1. Check:
- Intake air pressure sensor output voltage
Out of specification Replace the throttle
body.
a. Connect the pocket tester (DC 20 V) to the
throttle body sensor assembly coupler as
shown.
- Positive tester probe
pink/white "1" - Negative tester probe
gray/black "2"
b. Set the main switch to "ON".
c. Measure the intake air pressure sensor output voltage.
Throttle position sensor
1. Check:
Throttle position sensor
a. Connect the digital circuit tester to the terminals
of the throttle body sensor assembly
coupler as shown.
Positive tester probe →
gray/red t ...
Intake air temperature sensor
1. Check:
Intake air temperature sensor resistance
Out of specification Replace
the throttle
body.
a. Connect the pocket tester ( ×
1k) to the
throttle body sensor assembly co ...
Other materials:
Checking the rectifier/regulator
1. Check:
Rectifier/regulator output voltage
Out of specification → Replace the
rectifier/
regulator.
a. Set the engine tachometer to the spark plug
lead.
b. Connect the pocket tester (DC 20 V) to the
rectifier/regulator coupler as shown.
Positive tester probe
red "1"
Negat ...
Checking the ignition spark gap
1. Check:
Ignition spark gap
Out of specification Perform the
ignition
system troubleshooting, starting with step 5.
Refer to "TROUBLESHOOTING" on page
8-3.
NOTE:
If the ignition spark gap is within specification,
the ignition system circuit is operating normally.
a. Disconnect the spa ...
Installing the valves
The following procedure applies to all of the
valves and related components.
1. Deburr:
Valve stem end
(with an oil stone)
2. Lubricate:
Valve stem "1"
Valve stem seal "2"
(with the recommended lubricant)
3. Install:
Lower spring seat "1"
Valve stem seal "2"
V ...