Yamaha YZF-R125 Service Manual: Checking the fuel sender
1. Drain the fuel from the fuel tank.
2. Check:
Fuel sender resistance
Out of specification → Replace the fuel
sender.
a. Connect the pocket tester ( 
×
10) to the fuel
sender coupler as shown.
- Positive tester probe
sky blue "1" - Negative tester probe
orange/white "2"
A. Full fuel tank position
B. Empty fuel tank position
b. Measure the fuel sender resistance.
Checking the horn
1. Check:
Horn resistance
Out of specification Replace.
a. Disconnect the horn connectors from the
horn terminals.
b. Connect the pocket tester ( × 1) to the horn
terminals.
Positiv ...
Checking the speed sensor
1. Check:
Speed sensor output voltage
Out of specification → Replace.
a. Connect the pocket tester (DC 20 V) to the
speed sensor coupler (wire harness end) as
shown.
Positive tester pro ...
Other materials:
Assembling the crankcase
1. Thoroughly clean all the gasket mating surfaces
and crankcase mating surfaces.
2. Apply:
Sealant
(onto the crankcase mating surfaces)
NOTE:
Do not allow any sealant to come into contact
with the oil gallery.
3. Install:
Right crankcase
NOTE:
Turn the shift drum segment ...
Checking the ignition coil
1. Check:
Primary coil resistance
Out of specification Replace.
a. Disconnect the ignition coil connectors from
the ignition coil terminals.
b. Connect the pocket tester ( × 1)
to the ignition
coil as shown.
Positive tester probe
red/white "1"
Negative tester probe
orange ...
Faulty clutch
Clutch slips
1. Clutch
Improperly assembled clutch
Improperly adjusted clutch cable
Loose or fatigued clutch spring
Worn friction plate
Worn clutch plate
2. Engine oil
Incorrect oil level
Incorrect oil viscosity (low)
Deteriorated oil
Clutch drags
1. Clutch
Unevenly t ...