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

EMU39293

Cleaning and adjusting spark plug

The spark plug is an important engine compo-
nent. The condition of the spark plug can indi-
cate 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 outboard
motor to a Yamaha dealer. You should peri-
odically 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.
F2.5
1. Spark plug cap
F4, F6
1
1. Spark plug cap
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 another of the
correct type. WARNING! When remov-
ing or installing a spark plug, be care-
ful not to damage the insulator. A
damaged insulator could allow exter-
nal sparks, which could lead to explo-
sion or fire.
Standard spark plug:
F2.5MHA BR6HS
F4MHA CR6HSB
F6MHA 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.
Maintenance
[EWM00561]
83