Checking The Spark Plug - Yamaha YBR125ED Owner's Manual

PERIODIC MAINTENANCE AND MINOR REPAIR

Checking the spark plug

The spark plug is an important 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
in accordance with the periodic mainte-
nance and lubrication chart. In addition,
the condition of the spark plug can re-
veal the condition of the engine.
To remove the spark plug
1. Remove the spark plug cap.
6
1. Spark plug cap
2. Remove the spark plug as shown,
with the spark plug wrench includ-
ed in the owner's tool kit.
EAU19602
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 vehicle is
ridden normally).
NOTE:
If the spark plug shows a distinctly dif-
ferent color, the engine could be defec-
tive. Do not attempt to diagnose such
problems yourself. Instead, have a
Yamaha dealer check the vehicle.
2. Check the spark plug for electrode
erosion and excessive carbon or
other deposits, and replace it if
necessary.
To install the spark plug
1. Measure the spark plug gap with a
1. Spark plug gap
2. Clean the surface of the spark plug
6-8
Specified spark plug:
NGK/CR6HSA
wire thickness gauge and, if nec-
essary, adjust the gap to specifica-
tion.
Spark plug gap:
0.6–0.7 mm (0.024–0.028 in)
gasket and its mating surface, and
then wipe off any grime from the
spark plug threads.