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Periodic maintenance and adjustment
48
To install the top cover
1. Connect the main switch coupler and
auxiliary DC jack coupler, place the top
cover in the original position, and then
tighten the quick fastener screws.
2. Pass the brake hose, throttle cable, park-
ing brake cable and wire harness through
the cable guide, place the cable guide in
the original position, and then install the
screws.
3. Install the shroud.
NOTICE
ECS00372
● Make sure that all cables, hoses and
leads are routed properly before install-
ing the shroud and covers.
● When installing the shroud and covers,
be sure to tighten the fasteners secure-
ly.
ESU11783
Checking the spark plugs
The spark plugs are important engine compo-
nents and are easy to inspect. The condition
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 some-
thing wrong with the engine. For example, a
very white center electrode porcelain color
could indicate an intake track air leak or car-
buretion problem for that cylinder. Do not at-
tempt 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.
WARNING
EWS00710
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. Al-
so, if the reach is too short, carbon will form on
the exposed threads resulting in combustion
chamber hot spots and thread damage. Al-
ways use a spark plug with the specified
reach.
Specified spark plug:
Manufacturer:
NGK
Model:
CR9EB
Spark plug reach:
19.0 mm (0.75 in)
1. Spark plug gap
2. Spark plug reach
U8FP15E0.book Page 48 Thursday, July 23, 2009 11:01 AM