NOTE:
The engine speed, coolant temperature, and fault code, if detected, can be displayed on the LCD of the FI diagnostic tool when the tool is connected to the vehicle and is set to the normal mode.
1. Set the main switch to "OFF" and the engine stop switch to "
".
2. Disconnect the self-diagnosis signal connector "1", and then connect the FI diagnostic tool "2" as shown.
3. Set the main switch to "ON" and start the engine.
NOTE:
4. Stop the engine.
NOTE:
If a malfunction is detected in the system, the fault code appears on the
LCD of the FI diagnostic tool
and the "WARNING" LED (orange) comes on.

5. Set the main switch to "OFF" to cancel the normal mode.
6. Disconnect the FI diagnostic tool and connect the self-diagnosis signal connector.
Diagnostic mode
Setting the diagnostic modeIntroduction
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As the owner of the YZF-R125, you are benefiting from Yamaha's vast
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Separating the crankcase
1. Remove:
Crankcase bolts
NOTE:
Loosen each bolt 1/4 of a turn at a time, in stages
and in the proper sequence as shown.
A. Right crankcase
B. Left crankcase
2. Turn:
Shift drum segment
NOTE:
Turn the shift drum segment "1" to the position
shown in the illustration. In this ...
Checking the cylinder head
1. Eliminate:
Combustion chamber carbon deposits
(with a rounded scraper)
NOTE:
Do not use a sharp instrument to avoid damaging
or scratching:
Spark plug bore threads
Valve seats
2. Check:
Cylinder head
Damage/scratches Replace.
Cylinder head water jacket
Min ...