Yamaha YZF-R125 Service Manual: Checking the ignition timing
NOTE:
Prior to checking the ignition timing, check the wiring connections of the entire ignition system.
Make sure all connections are tight and free of corrosion.
1. Remove:
- Rider seat
- Left lower side cowling Refer to "GENERAL CHASSIS" on page 4-1.
2. Remove:
- Timing mark accessing screw "1"
3. Lift the fuel tank. (Do not disconnect the fuel hose, fuel drain hose, and couplers.) Refer to "FUEL TANK" on page 7-1.
4. Connect:
- Timing light "1"
- Digital tachometer
5. Check:
- Ignition timing
a. Start the engine, warm it up for several minutes,
and then let it run at the specified engine
idling speed. 
b. Check that stationary pointer "a" in the generator cover is within the firing range "b" on the generator rotor.
Incorrect firing range → Check the ignition system.
NOTE:
The ignition timing is not adjustable.
6. Remove:
- Digital tachometer
- Timing light
7. Install:
- Fuel tank Refer to "FUEL TANK" on page 7-1.
8. Install:
- Timing mark accessing screw
(along with the O-ring
)
9. Install:
- Left lower side cowling
- Right side cover
- Rider seat Refer to "GENERAL CHASSIS" on page 4-1.
Checking the spark plug
1. Remove:
Right side cover
Refer to "GENERAL CHASSIS" on page 4-1.
2. Disconnect:
Spark plug cap
3. Remove:
Spark plug
CAUTION:Before removing the spark plug, blow away
...
Measuring the compression pressure
NOTE:
Insufficient compression pressure will result in a
loss of performance.
1. Measure:
Valve clearance
Out of specification →Adjust.
Refer to "ADJUSTING THE VALVE CLEARANCE"
on page ...
Other materials:
Checking the water pump
1. Check:
Water pump housing cover
Water pump housing
Cracks/damage Replace.
Impeller shaft
Cracks/damage/wear Replace.
Bearing
Rough movement Replace.
Radiator outlet hose
Cracks/damage Replace.
...
Checking the steering head
1. Wash:
Bearings
Bearing races
2. Check:
Bearings
Bearing races
Damage/pitting →Replace.
3. Replace:
Bearings
Bearing races
a. Remove the bearing races from the steering
head pipe with a long rod "1" and hammer.
b. Remove the bearing race from the lower
bracket ...
Removing the rear wheel (disc)
1. Stand the vehicle on a level surface.
WARNINGSecurely support the vehicle
so that there is
no danger of it falling over.
2. Elevate:
Rear wheel
NOTE:
Place the vehicle on a suitable stand so that the
rear wheel is elevated.
3. Remove:
Rear brake caliper
NOTE: ...