Cleaning And Adjusting Spark Plug - Yamaha F2.5A Owner's Manual

Maintenance
EMU39295

Cleaning and adjusting spark plug

The spark plug is an important engine com-
ponent. The condition of the spark plug can
indicate something about the condition of the
engine. For example, if the center electrode
porcelain is very white, this could indicate an
intake air leak or carburetion problem in that
cylinder. Do not attempt to diagnose any
problems yourself. Instead, take the out-
board motor to a Yamaha dealer. You should
periodically remove and inspect the spark
plug because heat and deposits will cause
the spark plug to slowly break down and
erode.
1. Remove the spark plug cap from the
spark plug.
F2.5A
1. Spark plug cap
F4B, F5A, F6C
1
1. Spark plug cap
73
2. Remove the spark plug. If electrode ero-
sion becomes excessive, or if carbon
and other deposits are excessive, you
should replace the spark plug with an-
other of the correct type. WARNING!
When removing or installing a spark
plug, be careful not to damage the in-
sulator. A damaged insulator could al-
low external sparks, which could lead
to explosion or fire.
Standard spark plug:
F2.5AMH BR6HS
F4BMH CR6HSB
F5AMH CR6HSB
F6CMH CR6HSB
3. Be sure to use the specified spark plug,
otherwise the engine may not operate
properly. Before fitting the spark plug,
measure the electrode gap with a wire
thickness gauge; replace it if out of spec-
ification.
1
ZMU07373
1. Spark plug gap
2. Spark plug part number
3. Spark plug I.D. mark (NGK)
Spark plug gap:
0.6–0.7 mm (0.024–0.028 in)
ZMU06803
4. When fitting the plug, wipe off any dirt
from the threads, and then screw it in to
the correct torque.
[EWM00562]