Yamaha YZF-R125 Service Manual: 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 spark plug cap from the spark plug.
b. Connect the ignition checker "1" as shown.
2. Spark plug cap
c. Set the main switch to "ON" and the engine
stop switch to "
".
d. Measure the ignition spark gap "a".
e. Crank the engine by pushing the start switch
" 
" and gradually increase the
spark gap until
a misfire occurs.
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 ...
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 ...
Other materials:
Assembling the front wheel
1. Install:
Wheel bearings
Oil seal
a. Install the new wheel bearings and oil seal in
the reverse order of disassembly.
CAUTION:Do not contact the wheel bearing inner
race
"1" or balls "2". Contact should be made
only with the outer race "3".
NOTE:
Use a socket " ...
Installing the engine
1. Install:
Engine "1"
Engine mounting bolt (rear lower side) "2"
Engine mounting nut (rear lower side) "3"
Engine mounting bolt (rear upper side) "4"
Engine mounting nut (rear upper side) "5"
Engine mounting bolt (front side) "6"
Engine mounting nut (front side) "7"
NOTE:
Do not ...
Checking the front and rear brake pads
The front and rear brake pads must be
checked for wear at the intervals specified
in the periodic maintenance and
lubrication chart.
Front brake pads
Remove the front brake caliper by
removing the bolts.
Bolt
Brake caliper
Lining thickness
Check each front br ...