Yamaha YZ125(T)/T1 Owner's Service Manual page 210

IGNITION TIMING CHECK
EC372012
IGNITION TIMING CHECK
1. Remove:
9 Fuel tank
Refer to "SEAT, FUEL TANK AND SIDE
COVERS" section in the CHAPTER 4.
9 Spark plug
9 Crankcase cover (left)
2. Attach:
9 Dial gauge 1
9 Spark plug hole dial stand 2
3. Rotate the magneto rotor 1 until the
piston reaches top dead center (TDC).
When this happens, the needle on the dial
gauge will stop and reverse directions even
though the rotor is being turned in the same
direction.
4. Set the dial gauge to zero at TDC.
5. From TDC, rotate the rotor clockwise
until the dial gauge indicates that the
piston is at a specified distance from TDC.
6. Check:
9 Ignition timing
Punch mark a on rotor should be aligned
with punch mark b on stator.
Not aligned ¡ Adjust.
3-39
INSP
ADJ
Dial gauge:
YU-3097/90890-01252
Spark plug hole dial stand:
YU-1256
Ignition timing (B.T.D.C.):
0.48 mm (0.019 in)