2008 YAMAHA XT660X engine

PERIODIC MAINTENANCE AND MINOR REPAIR
6-9
6
EAU19603
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.
2. Remove the spark plug as shown,
with the spark plug wrench includ-
ed in the owner’s tool kit.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 oper-
ating improperly. Do not attempt to
diagnose such problems yourself. In-
stead, have a Yamaha dealer checkthe 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
wire thickness gauge and, if nec-
essary, adjust the gap to specifica-
tion.
1. Spark plug cap
1. Spark plug wrench
Specified spark plug:
NGK/CR7E
1. Spark plug gap
Spark plug gap:
0.7–0.8 mm (0.028–0.031 in)
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PERIODIC MAINTENANCE AND MINOR REPAIR
6-10
62. Clean the surface of the spark plug
gasket and its mating surface, and
then wipe off any grime from the
spark plug threads.
3. Install the spark plug with the
spark plug wrench, and then tight-
en it to the specified torque.
NOTE:
If a torque wrench is not available when
installing a spark plug, a good estimate
of the correct torque is 1/4–1/2 turn
past finger tight. However, the spark
plug should be tightened to the speci-fied torque as soon as possible.
4. Install the spark plug cap.
EAUM1841
Engine oil and oil filter ele-
ment The engine oil level should be checked
before each ride. In addition, the oil
must be changed and the oil filter ele-
ment replaced at the intervals specified
in the periodic maintenance and lubri-
cation chart.
To check the engine oil level
1. Place the vehicle on a level sur-
face and hold it in an upright posi-
tion.NOTE:
Make sure that the vehicle is positioned
straight up when checking the oil level.
A slight tilt to the side can result in afalse reading.
2. Start the engine, warm it up for 10–
15 minutes, and then turn it off.
3. Wait a few minutes until the oil set-
tles, remove the oil filler cap, wipe
the dipstick clean, insert it back
into the oil filler hole (without
screwing it in), and then remove it
again to check the oil level.
NOTE:

The engine oil tank is located in-
side of the frame.


The engine oil should be between
the minimum and maximum levelmarks.
CAUTION:
ECA10010
Do not operate the vehicle until you
know that the engine oil level is suf-ficient.
Tightening torque:
Spark plug:
12.5 Nm (1.25 m·kgf, 9.0 ft·lbf)
1. Engine oil filler cap
2. Maximum level mark
3. Minimum level mark
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PERIODIC MAINTENANCE AND MINOR REPAIR
6-11
6
WARNING
EWA10360
Never remove the engine oil tank
cap after high-speed operation, oth-
erwise hot engine oil could spout
out and cause damage or injury. Al-
ways let the engine oil cool down
sufficiently before removing the oiltank cap.
4. If the engine oil is below the mini-
mum level mark, add sufficient oil
of the recommended type to raise
it to the correct level.
5. Install the oil filler cap.
To change the engine oil (with or
without oil filter element replace-
ment)
1. Start the engine, warm it up for
several minutes, and then turn it
off.
2. Install the engine oil drain attach-
ment, provided with the owner’s
tool kit, under the drain bolt of the
crankcase.3. Place an oil pan under the engine
to collect the used oil.
4. Remove the engine oil filler cap
and the drain bolt to drain the oil
from the crankcase.
5. Remove the drain bolt to drain the
oil from the oil tank.6. Remove the oil filter element drain
bolt to drain the oil from the oil filter
element.
NOTE:
Skip steps 7–9 if the oil filter element isnot being replaced.
7. Remove the oil filter element cover
by removing the bolts.
1. Engine oil drain bolt (crankcase)
2. Engine oil drain attachment
1. Engine oil drain bolt (oil tank)
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PERIODIC MAINTENANCE AND MINOR REPAIR
6-12
68. Remove and replace the oil filter
element and O-rings.9. Install the oil filter element cover by
installing the bolts and the oil filter
element drain bolt, then tightening
them to the specified torques.
NOTE:Make sure that the O-rings are properlyseated.
10. Install the oil drain bolts, and then
tighten them to the specified
torques.
11. Add the specified amount of the
recommended engine oil, and then
install and tighten the oil filler cap.
CAUTION:
ECAM1060
The engine oil tank must be filled in
2 steps. First, fill the engine oil tank
with 1.90 L (2.0 US qt) (1.67 Imp.qt) of
the recommended engine oil. Then,
start the engine, race it 5 or 6 times,
turn it off, and then add the remain-der of the engine oil.CAUTION:
ECA11620


In order to prevent clutch slip-
page (since the engine oil also
lubricates the clutch), do not
mix any chemical additives. Do
not use oils with a diesel speci-
fication of “CD” or oils of a high-
er quality than specified. In
1. Oil filter element cover bolt
2. Oil filter element drain bolt
1. Oil filter element
2. O-ring
Tightening torques:
Oil filter element cover bolt:
10 Nm (1.0 m·kgf, 7.2 ft·lbf)
Oil filter element drain bolt:
10 Nm (1.0 m·kgf, 7.2 ft·lbf)
Tightening torques:
Engine oil drain bolt (crankcase):
30 Nm (3.0 m·kgf, 22 ft·lbf)
Engine oil drain bolt (oil tank):
18 Nm (1.8 m·kgf, 13 ft·lbf)
Recommended engine oil:
See page 8-1.
Oil quantity:
Without oil filter element replace-
ment:
2.50 L (2.64 US qt) (2.20 Imp.qt)
With oil filter element replacement:
2.60 L (2.75 US qt) (2.29 Imp.qt)
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PERIODIC MAINTENANCE AND MINOR REPAIR
6-13
6 addition, do not use oils labeled
“ENERGY CONSERVING II” or
higher.


Make sure that no foreign mate-rial enters the crankcase.
12. Start the engine, and then let it idle
for several minutes while checking
it for oil leakage. If oil is leaking, im-
mediately turn the engine off and
check for the cause.
13. Turn the engine off, and then
check the oil level and correct it if
necessary.
EAU20070
Coolant The coolant level should be checked
before each ride. In addition, the cool-
ant must be changed at the intervals
specified in the periodic maintenance
and lubrication chart.
EAUM1722
To check the coolant level
1. Place the vehicle on a level sur-
face and hold it in an upright posi-
tion.NOTE:

The coolant level must be checked
on a cold engine since the level
varies with engine temperature.


Make sure that the vehicle is posi-
tioned straight up when checking
the coolant level. A slight tilt to theside can result in a false reading.
2. Check the coolant level in the cool-
ant reservoir.
NOTE:The coolant should be between theminimum and maximum level marks.3. If the coolant is at or below the
minimum level mark, remove cowl-
ing B (See page 6-5.), and then
open the reservoir cap.
4. Add coolant to the maximum level
mark, and then close the reservoir
cap.
1. Coolant reservoir
2. Maximum level mark
3. Minimum level mark
Coolant reservoir capacity (up to the
maximum level mark):
0.25 L (0.26 US qt) (0.22 Imp.qt)
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PERIODIC MAINTENANCE AND MINOR REPAIR
6-14
6
CAUTION:
ECA10471


If coolant is not available, use
distilled water or soft tap water
instead. Do not use hard water
or salt water since it is harmful
to the engine.


If water has been used instead
of coolant, replace it with cool-
ant as soon as possible, other-
wise the cooling system will not
be protected against frost and
corrosion.


If water has been added to the
coolant, have a Yamaha dealer
check the antifreeze content of
the coolant as soon as possible,
otherwise the effectiveness ofthe coolant will be reduced.WARNING
EWA10380
Never attempt to remove the radiatorcap when the engine is hot.
5. Install the cowling.
NOTE:

The radiator fan is automatically
switched on or off according to the
coolant temperature in the radia-
tor.


If the engine overheats, see page6-40 for further instructions.
EAUM1802
To change the coolant
1. Place the vehicle on a level sur-
face and let the engine cool if nec-
essary.
2. Remove the seat and panel B.
(See pages 3-12 and 6-5.)
3. Remove cowling B. (See page
6-5.)
4. Place a container under the engine
to collect the used coolant.
5. Loosen the radiator cap retainer
screw.
6. Remove the radiator cap and cool-
ant reservoir cap.
WARNING
EWA10380
Never attempt to remove the radiatorcap when the engine is hot.7. Remove the coolant reservoir
bolts, and then turn the coolant
reservoir upside down to empty it.
8. Install the coolant reservoir by
placing it in the original position,
then installing the bolts.
1. Radiator cap
2. Radiator cap retaining screw
3. Radiator cap retainer
4. Coolant reservoir cap
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PERIODIC MAINTENANCE AND MINOR REPAIR
6-15
6 9. Remove the coolant drain bolt to
drain the cooling system.
10. After the coolant is completely
drained, thoroughly flush the cool-
ing system with clean tap water.11. Install the coolant drain bolt, and
then tighten it to the specified
torque.
NOTE:Check the washer for damage and re-place it if necessary.
12. Pour the specified amount of the
recommended coolant into the ra-
diator and reservoir.
CAUTION:
ECA10471


If coolant is not available, use
distilled water or soft tap water
instead. Do not use hard water
or salt water since it is harmful
to the engine.


If water has been used instead
of coolant, replace it with cool-
ant as soon as possible, other-
wise the cooling system will not
be protected against frost and
corrosion.


If water has been added to the
coolant, have a Yamaha dealer
check the antifreeze content of
the coolant as soon as possible,
otherwise the effectiveness ofthe coolant will be reduced.
13. Install the coolant reservoir cap.
14. Install the radiator cap and radiator
cap retainer by installing the
screw.
15. Start the engine, let it idle for sev-
eral minutes, and then turn it off.
1. Bolt
1. Coolant drain bolt
Tightening torque:
Coolant drain bolt:
11 Nm (1.1 m·kgf, 8.0 ft·lbf)
Antifreeze/water mixture ratio:
1:1
Recommended antifreeze:
High-quality ethylene glycol anti-
freeze containing corrosion inhibitors
for aluminum engines
Coolant quantity:
Radiator capacity (including all
routes):
1.00 L (1.06 US qt) (0.88 Imp.qt)
Coolant reservoir capacity (up to the
maximum level mark):
0.25 L (0.26 US qt) (0.22 Imp.qt)
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PERIODIC MAINTENANCE AND MINOR REPAIR
6-16
616. Check the coolant level in the res-
ervoir. If necessary, remove the
coolant reservoir cap, add coolant
to the maximum level mark, and
then install the cap.
17. Start the engine, and then check
the vehicle for coolant leakage. If
coolant is leaking, have a Yamaha
dealer check the cooling system.
18. Install the cowling, the panel and
the seat.
EAUM1833
Replacing the air filter element
and cleaning the check hose The air filter element should be re-
placed at the intervals specified in the
periodic maintenance and lubrication
chart. Replace the air filter element
more frequently if you are riding in un-
usually wet or dusty areas. In addition,
the air filter check hose must be fre-
quently checked and cleaned if neces-
sary.
To replace the air filter element
1. Remove the seat. (See page
3-12.)
2. Remove panel B. (See page 6-5.)
3. Remove the air filter case cover by
removing the screws.4. Pull the air filter element out.
5. Insert a new air filter element into
the air filter case as shown.
1. Air filter case cover
2. Screw
1. Air filter element
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