Checking The Spark Plugs - Yamaha GCH I 237 Owner's Manual

Periodic maintenance and adjustment
3
1
1. Screw
2. Bolt
3. Right side cover
To install the right side cover
1. Place the right side cover in the original
position, and then tighten the bolts and
screws.
2. Close the shroud.
ECS01041
NOTICE
 Make sure that all cables, leads, and
hoses are routed properly before clos-
ing the shroud and installing the right
side cover.
 When installing the right side cover, be
sure to tighten the bolts and screws se-
curely.
ESU11785

Checking the spark plugs

The spark plugs are important engine com-
ponents and are easy to inspect. The condi-
tion of the spark plugs can indicate the
condition of the engine.
Check the coloration on the white porcelain
insulator around the center electrode. The
ideal coloration at this point is a medium-to-
light tan color for a snowmobile that is being
ridden normally. If any spark plug shows a
distinctly different color, there could be
something wrong with the engine. For exam-
ple, a very white center electrode porcelain
color could indicate an intake track air leak or
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2 1
carburetion problem for that cylinder. Do not
attempt to diagnose such problems yourself.
Instead, take the snowmobile to a Yamaha
dealer for inspection and possible repairs.
You should periodically remove and inspect
the spark plugs because heat and deposits
will cause any spark plug to slowly break
down and erode. Consult a Yamaha dealer
before changing to a different type of spark
plug.
Specified spark plug:
Manufacturer:
NGK
Model:
CR8E
EWS00711
WARNING
Be sure to use the specified spark plug
and spark plug cap. Otherwise, the
T.O.R.S. may not work properly.
Spark plugs are produced in several different
thread lengths. The thread length or reach is
the distance from the spark plug gasket seat
to the end of the threaded portion. If the
reach is too long, overheating and engine
damage may result. If the reach is too short,
spark plug fouling and poor performance
may result. Also, if the reach is too short, car-
bon will form on the exposed threads result-
ing in combustion chamber hot spots and
thread damage. Always use a spark plug with
the specified reach.
Spark plug reach:
19.0 mm (0.75 in)