Checking The Spark Plug - Yamaha YBR250 Owner's Manual

1. Remove the seat. (See page 3-9.)
2. Remove the screws, and then pull
the panel to the outside as shown.
To install the panel
1. Place the panel in the original
position, and install the screws.
2. Install the seat.
PERIODIC MAINTENANCE AND MINOR REPAIR

Checking the spark plug

The spark plug is an important
l
engine component, which is easy
to check. Since heat and deposits
will cause any spark plug to slowly
erode, the spark plug should be
removed and checked
accordance with the periodic
maintenance and lubrication chart.
In addition, the condition of the
spark plug can reveal the condition
of the engine.
To remove the spark plug
1. Remove cowling. (See page 6-6.)
1. Spark plug cap
2. Remove the spark plug cap.
3. Remove the spark plug as shown,
with the spark plug wrench included
in the owner's tool kit.
6 - 7
EAU19630
in
1. Spark plug wrench
To check the spark plug
1. Check that the porcelain insulator
around the center electrode of the
spark plug is a medium-to-light tan
(the ideal color when the
motorcycle is ridden normally).
If the spark plug shows a distinctly
different color, the engine could be
defective. Do not attempt to diagnose
such problems yourself. Instead, have
a Yamaha dealer check the motorcycle.
2. Check the spark plug for electrode
erosion and excessive carbon or
other deposits, and replace it if
necessary.
6