Ignition Timing - Yamaha YTZ250S 1986 Service Manual

Ignition Timing
The ignition timing must be set precisely to
ensure that the ignition spark occurs at the
proper time to provide optimum engine
power.
1. Remove , the spark plug, left side cover,
change pedal, and the left-hand
crankcase cover.
2. Install the extension on the dial gauge,
and slide the dial gauge assembly into
the dial gauge stand.
3. Screw the dial gauge stand into the
spark plug hole.
4. Rotate the magneto rotor until the piston
reaches top dead center (TOC). 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. Zero the dial gauge at
TOC.
5. From TOC, rotate the rotor clockwise
until the dial gauge indicates that the
piston is at a specified distance from
TOC. At this point, the scribed marks on
the rotor and the stator plate should be
aligned.
2-7
Ignition timing: B.T.O.C.
1.27 ±O.l
mm
(O.05±O.004
in)
,
1. Rotor mark 2. Stator mark 3. Crankcase mark
6. If the marks are not aligned, loosen the
two stator retaining screws and rotate
the stator until the marks line up. Tighten
the screws and recheck the timing
marks.
1. Retaining screws
7. Remove the dial gauge assembly and
stand, and reinstall the spark plug. Tor-
que the plug to specification.
Spark plug torque:
25 Nm (2.5 m'kg, 18 ft·lb)
8. Reinstall the left-hand crankcase cover,
change pedal and left side cover.