Electrical - Yamaha YZ250F(X) Owner's Service Manual

ELECTRICAL

CHECKING THE SPARK PLUG
1. Remove:
• Spark plug
2. Inspect:
• Electrode "1"
→
Wear/damage Replace.
• Insulator color "2"
Normal condition is a medium to
light tan color.
Distinctly different color
the engine condition.
When the engine runs for many hours
at low speeds, the spark plug insula-
tor will become sooty, even if the en-
gine and carburetor are in good
operating condition.
3. Measure:
• Plug gap "a"
Use a wire gauge or thickness
gauge.
→
Out of specification
Spark plug gap:
0.7–0.8 mm (0.028–
0.031 in)
4. Clean the plug with a spark plug
cleaner if necessary.
5. Tighten:
• Spark plug
Spark plug:
13 Nm (1.3 m•kg, 9.4
ft•lb)
• Before installing a spark plug, clean
the gasket surface and plug sur-
face.
• Finger-tighten "a" the spark plug
before torquing to specification "b".
CHECKING THE IGNITION TIMING
1. Remove:
• Timing mark accessing screw "1"
2. Attach:
• Timing light
• Inductive tachometer
→
Check
To the ignition coil lead (orange
lead"1").
Timing light:
3. Adjust:
• Engine idling speed
Refer to "ADJUSTING THE EN-
GINE IDLING SPEED" section.
4. Check:
• Ignition timing
Visually check the stationary
Regap.
pointer "a" is within the firing
range "b" on the rotor.
Incorrect firing range
tor and pickup assembly.
5. Install:
• Timing mark accessing screw
YM-33277-A/90890-
03141
→
Check ro-
3-23
ELECTRICAL