Checking The Spark Plug - Yamaha YFZ 2018 Owner's Manual

1. Quick fastener
8
1
1
1. Quick fastener
To install the cowling
1. Place the cowling in the original position, and
2. Install panels C, B and A.
1
EBU29442

Checking the spark plug

The spark plug is an important engine component,
which should be checked periodically, preferably
1
by a Yamaha dealer. Since heat and deposits will
cause any spark plug to slowly erode, the spark
plug should be removed and checked in accor-
dance with the periodic maintenance and lubrica-
tion chart. In addition, the condition of the spark
plug can reveal the condition of the engine.
The porcelain insulator around the center elec-
trode of the spark plug should be a medium-to-
light tan (the ideal color when the vehicle is ridden
normally). If the spark plug shows a distinctly dif-
ferent color, the engine could be operating im-
properly. Do not attempt to diagnose such
problems yourself. Instead, have a Yamaha dealer
check the vehicle.
If the spark plug shows signs of electrode erosion
and excessive carbon or other deposits, it should
be replaced.
8-13
then tighten the quick fasteners.