Yamaha YZF-R125 Service Manual: Checking the fuel pressure
1. Check:
- Pressure regulator operation
a. Remove the fuel hose connector cover "1" and disconnect the fuel hose "2" from the fuel pump.
| CAUTION: Although the fuel has been removed from the fuel tank, be careful when removing the fuel hose, since there may be fuel remaining in it. |
NOTE:
Before removing the hose, place a few rags in the area under where it will be removed.
b. Connect the pressure gauge "3" and fuel
pressure adapter "4".
c. Start the engine.
d. Measure the fuel pressure. 
Faulty Replace the fuel tank (with fuel pump).
e. Connect the fuel hose and install the fuel hose connector cover.
Refer to "INSTALLING THE FUEL HOSE" on page 7-2.
Installing the fuel hose
1. Install:
Fuel hose
Fuel hose connector cover
CAUTION:When installing the fuel hose, make sure
that
it is securely connected, and that the fuel
hose connector cover is in t ...
Throttle body
...
Other materials:
Checking the shift shaft
1. Check:
Shift shaft
Bends/damage/wear Replace.
Shift shaft spring
Damage/wear Replace.
Checking the stopper lever
1. Check:
Stopper lever
Bends/damage Replace.
Roller turns roughly Replace
the stopper
lever.
Stopper lever spring
Damage/wear Replace.
...
Disassembling the front wheel
1. Remove:
Oil seal
Wheel bearings
a. Clean the surface of the front wheel hub.
b. Remove the oil seal "1" with a flat-head
screwdriver.
NOTE:
To prevent damaging the wheel, place a rag "2"
between the screwdriver and the wheel surface.
c. Remove the wheel bearings "3" with a ge ...
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 probe
gray "1"
Negative tester probe
gray/black "2"
b. Set the main switch to "ON".
c. ...