2008 Yamaha Motorsports Apex LTX GT Owners Manual - Page 50

2008 Yamaha Motorsports Apex LTX GT Manual

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Periodic maintenance G G Keep your body and clothing away from rotating parts when servicing the snowmobile with the shroud or covers removed. Do not touch the hot muffler and engine during or immediately after operation. Specified spark plug: Manufacturer: NGK Model: CR9EB 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, carbon will form on the exposed threads resulting 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) ECS00370 CAUTION: Make sure that all cables, leads, etc., are routed properly before installing the shroud and covers. NOTE: When installing the shroud and covers, be sure to tighten the fasteners and the top cover bolts securely. ESU11780 Checking the spark plugs The spark plug is an important engine component and is easy to inspect. The condition of the spark plug 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 a light tan color for a snowmobile that is being ridden normally. If a spark plug shows a distinctly different color, there could be something wrong with the engine. For example, a very white center electrode porcelain color could indicate an intake track air leak or 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 plug because heat and deposits will cause a spark plug to slowly break down and erode. Consult a Yamaha dealer before changing to a different type of spark plug. 1. Spark plug gap 2. Spark plug reach Before installing any spark plug, measure the electrode gap with a wire thickness gauge and adjust to specification. Spark plug gap: 0.7-0.8 mm (0.028-0.031 in) 44

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Periodic maintenance
44
●
Keep your body and clothing away from
rotating parts when servicing the snow-
mobile with the shroud or covers re-
moved.
●
Do not touch the hot muffler and engine
during or immediately after operation.
CAUTION:
ECS00370
Make sure that all cables, leads, etc., are
routed properly before installing the
shroud and covers.
NOTE:
When installing the shroud and covers, be
sure to tighten the fasteners and the top cover
bolts securely.
ESU11780
Checking the spark plugs
The spark plug is an important engine compo-
nent and is easy to inspect. The condition of
the spark plug 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 a
light tan color for a snowmobile that is being
ridden normally. If a spark plug shows a dis-
tinctly 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 plug because heat and deposits will
cause a spark plug to slowly break down and
erode. Consult a Yamaha dealer before
changing to a different type of spark plug.
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.
Before installing any spark plug, measure the
electrode gap with a wire thickness gauge
and adjust to specification.
Specified spark plug:
Manufacturer:
NGK
Model:
CR9EB
Spark plug reach:
19.0 mm (0.75 in)
1.
Spark plug gap
2.
Spark plug reach
Spark plug gap:
0.7–0.8 mm (0.028–0.031 in)