Yamaha YZF-R125 Service Manual: Checking the lean angle sensor
1. Remove:
- Lean angle sensor
2. Check:
Lean angle sensor output voltage
Out of specification 
Replace.
a. Connect the lean angle sensor to the wire harness.
b. Connect the pocket tester (DC 20 V) to the
lean angle sensor coupler as shown.
Positive tester probe 
yellow/green "1"
Negative tester probe 
gray/black "2"
c. Set the main switch to "ON".
d. Tilt the lean angle sensor to 65.
e. Measure the lean angle sensor output voltage.
Checking the crankshaft position sensor
1. Disconnect:
Crankshaft position sensor coupler
(from the wire harness)
2. Check:
Crankshaft position sensor resistance
Out of specification Replace
the crankshaft
position senso ...
Checking the starter motor operation
1. Check:
Starter motor operation
Does not operate → Perform the electric
starting system troubleshooting, starting with
step 4.
Refer to "TROUBLESHOOTING" on page
8-9.
a. Con ...
Other materials:
Removing the primary drive gear and balancer gears
1. Loosen:
Primary drive gear nut "1"
NOTE:
Place the aluminum plate "a" between the balancer
drive gear "2" and the balancer driven
gear "3", and then loosen the primary drive gear
nut.
2. Straighten the lock washer tab.
3. Loosen:
Balancer driven gear nut "1"
NOTE:
Place ...
Removing the starter clutch
1. Remove:
Starter clutch bolts "1"
NOTE:
While holding the generator rotor "2" with the
sheave holder "3", remove the starter clutch
bolts.
Do not allow the sheave holder to touch the
projection on the generator rotor.
...
Checking the radiator
1. Check:
Radiator fins
obstruction clean.
Apply compressed air to the rear of the radiator.
Damage repair or replace.
NOTE:
Straighten any flattened fins with a thin, flat-head
screwdriver.
2. Check:
Radiator hoses
Cracks/damage Replace.
3. Measure:
Radiator cap ...