Yamaha YZF-R125 Service Manual: 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 any dirt accumulated in the spark plug well with compressed air to prevent it from falling into the cylinder. |
4. Check:
Spark plug type
Incorrect →Change.
5. Check:
- Electrode "1" Damage/wear→ Replace the spark plug.
- Insulator "2"
Abnormal color→ Replace the spark plug.
Normal color is medium-to-light tan.
6. Clean:
- Spark plug (with a spark plug cleaner or wire brush)
7. Measure:
- Spark plug gap "a"
(with a wire thickness gauge)
Out of specification → Regap.
8. Install:
- Spark plug
NOTE:
Before installing the spark plug, clean the spark plug and gasket surface.
9. Connect:
- Spark plug cap
10.Install:
- Right side cover Refer to "GENERAL CHASSIS" on page 4-1.
Adjusting the throttle cable free play
NOTE:
Prior to adjusting the throttle cable free play, the
engine idling speed should be adjusted.
1. Check:
Throttle cable free play "a"
Out of specification →Adjust.
2. Remov ...
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
L ...
Other materials:
Handlebar switches
Left
Left
1. Pass switch "PASS"
2. Dimmer switch "/"
3. Turn signal switch "/"
4. Horn switch""
Right
Right
Engine stop switch "/"
Start switch""
Pass switch "PASS"
Press this switch to flash the headlight.
Dimmer switch "/"
Set this switch to""
for the high
beam an ...
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 rectifier/regulator
1. Check:
Rectifier/regulator output voltage
Out of specification → Replace the
rectifier/
regulator.
a. Set the engine tachometer to the spark plug
lead.
b. Connect the pocket tester (DC 20 V) to the
rectifier/regulator coupler as shown.
Positive tester probe
red "1"
Negat ...