Yamaha YZF-R125 Service Manual: Troubleshooting
The ignition system fails to operate (no spark or intermittent spark).
NOTE:
- Before troubleshooting, remove the following part(s):
1. Seats
2. Fuel tank
3. Right side cover
4. Left side panel
5. Left upper side cowling
Circuit diagram
2. Crankshaft position sensor
4. Main fuse
5. Main switch
8. Sidestand switch
9. Battery
17.Engine stop switch
23.Lean angle sensor
25.ECU (engine control unit)
26.Ignition coil
27.Spark ...
Other materials:
Checking the front wheel
1. Check:
Front wheel axle
Roll the wheel axle on a flat surface.
Bends → Replace.
WARNINGDo not attempt to straighten a bent wheel
axle.
2. Check:
Tire
Front wheel
Damage/wear → Replace.
Refer to "CHECKING THE TIRES" on page
3-23 and "CHECKING TH ...
Checking the timing chain tensioner
1. Check:
Timing chain tensioner
Cracks/damage/rough movement Replace.
a. Lightly press the timing chain tensioner rod
into the timing chain tensioner housing by
hand.
NOTE:
While pressing the timing chain tensioner rod,
wind it clockwise with a thin screwdriver "1" until
it stops.
b. ...
Checking the rocker arms and rocker arm shafts
The following procedure applies to all of the
rocker arms and rocker arm shafts.
1. Check:
Rocker arm
Damage/wear Replace.
2. Check:
Rocker arm shaft
Blue discoloration/excessive wear/pitting/
scratches Replace or
check the lubrication
system.
3. Measure:
Rocke ...