Page 97 of 154
8-10
8 To remove the spark plug
1. Remove the spark plug cap.
2. Remove the spark plug as shown, with the
spark plug wrench included 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 medi-
um-to-light tan (the ideal color when the ATV
is ridden normally).
TIPIf the spark plug shows a distinctly different color,
the engine could be operating improperly. Do not
attempt to diagnose such problems yourself. In-
stead, have a Yamaha dealer check the ATV.
1. Spark plug cap
1
1. Spark plug wrench
1
U1AS61E0.book Page 10 Thursday, February 11, 2010 2:17 PM
Page 99 of 154

8-12
8
EBU26786Engine oil and oil filter element The engine oil level should be checked before
each ride. In addition, the oil must be changed and
the oil filter element replaced at the intervals spec-
ified in the periodic maintenance and lubrication
chart.
To check the engine oil level
1. Place the ATV on a level surface.
2. Start the engine, warm it up until the engine oil
has reached a normal temperature of 60 °C
(140 °F), let it continue to idle for ten seconds
or more, and then turn the engine off.TIPTo achieve the proper engine oil temperature for
an accurate oil level reading, the engine must have
first completely cooled down, and then warmed up
again for several minutes to normal operating tem-
perature.3. Remove the engine oil tank filler cap, and then
wipe the engine oil dipstick off with a clean
rag.
4. Insert the dipstick in the filler hole (without
screwing it in), and then remove it again to
check the oil level.
TIPThe engine oil should be between the minimum
and maximum level marks.5. If the engine oil is at or below the minimum
level mark, add sufficient oil of the recom-
mended type through the engine oil tank filler
hole to raise it to the correct level. NOTICE:1. Engine oil tank
2. Engine oil tank filler cap
3. Engine oil dipstick
4. Maximum level mark
5. Minimum level mark
2
3
4
5
1 2
U1AS61E0.book Page 12 Thursday, February 11, 2010 2:17 PM
Page 103 of 154

8-16
8 14. Remove the engine oil tank filler cap, and then
gradually fill the oil tank with the remaining oil
quantity while regularly checking the oil level
on the dipstick.
15. Install and tighten the engine oil tank filler cap.
TIPBe sure to wipe off spilled oil on any parts after the
engine and exhaust system have cooled down.NOTICEECB00300In order to prevent clutch slippage (since the
engine oil also lubricates the clutch), do not
mix any chemical additives. Do not use oils
with a diesel specification of “CD” or oils ofa higher quality than specified. In addition,
do not use oils labeled “ENERGY CONSERV-
ING II” or higher.
Make sure that no foreign material enters the
crankcase.16. Start the engine, and then let it idle for several
minutes while checking it for oil leakage. If oil
is leaking, immediately turn the engine off and
check for the cause.
17. Turn the engine off, and then check the oil lev-
el and correct it if necessary.EBU23470Coolant The coolant level should be checked before each
ride. In addition, the coolant must be changed at
the intervals specified in the periodic maintenance
and lubrication chart.EBU27941To check the coolant level
1. Place the ATV on a level surface. Recommended oil:
See page 10-1.
Oil quantity:
Without oil filter element replacement:
1.75 L (1.85 US qt, 1.54 Imp.qt)
With oil filter element replacement:
1.85 L (1.96 US qt, 1.63 Imp.qt)
U1AS61E0.book Page 16 Thursday, February 11, 2010 2:17 PM
Page 104 of 154

8-17
8
TIPThe coolant level must be checked on a cold en-
gine since the level varies with engine tempera-
ture.2. Check the coolant level in the coolant reser-
voir.TIPThe coolant should be between the minimum and
maximum level marks.
3. If the coolant is at or below the minimum level
mark, remove the coolant reservoir cap, add
coolant or distilled water to the maximum level
mark, and then install the reservoir cap.
NOTICE: If coolant is not available, use
distilled water or soft tap water instead. Do
not use hard water or salt water since they
are harmful to the engine. If water has
been used instead of coolant, replace it
with coolant as soon as possible, other-
wise the cooling system will not be pro-
tected against frost and corrosion. If water
has been added to the coolant, have a
Yamaha dealer check the antifreeze con-
tent of the coolant as soon as possible,
otherwise the effectiveness of the coolant
will be reduced.
[ECB01011]
1. Maximum level mark
2. Minimum level mark
12
U1AS61E0.book Page 17 Thursday, February 11, 2010 2:17 PM
Page 107 of 154

8-20
8 9. Connect the coolant reservoir hose.
10. Pour the recommended coolant into the reser-
voir to the maximum level mark, and then in-
stall the reservoir cap. NOTICE: Mix
antifreeze with distilled water only. Howev-
er, if distilled water is not available, soft
water may be used for refilling. Do not use
hard water or salt water since they are
harmful to the engine.
[ECB00991]
11. Pour the recommended coolant into the radia-
tor until it is full.
12. Install the radiator cap, start the engine, let it
idle for several minutes, and then turn it off.13. Remove the radiator cap to check the coolant
level in the radiator. If it is low, add sufficient
coolant until it reaches the top of the radiator,
and then install the radiator cap.
14. Start the engine, and then check for coolant
leakage.
TIPIf any leakage is found, have a Yamaha dealer
check the cooling system.15. Install the panel.EBU26805Cleaning the air filter element The air filter element should be cleaned at the in-
tervals specified in the periodic maintenance and
lubrication chart. Clean or, if necessary, replace
the air filter element more frequently if you are
riding in unusually wet or dusty areas.TIPThere is a check hose at the bottom of the air filter
case. If dust or water collects in this hose, empty
the hose and clean the air filter element and air fil-
ter case.
Antifreeze/water mixture ratio:
1:1
Recommended antifreeze:
High-quality ethylene glycol antifreeze con-
taining corrosion inhibitors for aluminum en-
gines
Coolant quantity:
Radiator capacity (including all routes):
1.61 L (1.70 US qt, 1.42 Imp.qt)
Coolant reservoir capacity (up to the maxi-
mum level mark):
0.25 L (0.26 US qt, 0.22 Imp.qt)
U1AS61E0.book Page 20 Thursday, February 11, 2010 2:17 PM
Page 111 of 154

8-24
8 15. Insert the air filter element into the air filter
case, and then tighten the wing bolt. NOTICE:
Make sure that the air filter element is
properly seated in the air filter case. Never
operate the engine with the air filter ele-
ment removed. This will allow unfiltered air
to enter the engine, causing rapid engine
wear and possible engine damage. Addi-
tionally, operation without the air filter ele-
ment will affect the fuel injection system
with subsequent poor performance and
possible engine overheating.
[ECB00761]
16. Install the air filter case cover by hooking the
holders onto the air filter case.17. Install the seat.
TIPThe air filter element should be cleaned every 20–
40 hours. It should be cleaned and lubricated more
often if the ATV is operated in extremely dusty ar-
eas. Each time the air filter element maintenance
is performed, check the air inlet of the air filter case
for obstructions. Check the air filter case rubber
joint to the throttle body and the rubber joint mani-
fold fittings for an air-tight seal. Tighten all fittings
securely to avoid the possibility of unfiltered air en-
tering the engine.EBU27702Cleaning the spark arrester Select a well-ventilated area free of combustible
materials and make sure the exhaust and muffler
are cool.
1. Remove the bolt.
1. Washer
1
U1AS61E0.book Page 24 Thursday, February 11, 2010 2:17 PM
Page 113 of 154

8-26
8 7. Start the engine and rev it up approximately
twenty times while momentarily creating ex-
haust system back pressure by blocking the
end of the muffler with a shop towel.
8. Stop the engine and allow the exhaust pipe to
cool.
9. Check the gasket for damage, and replace it if
necessary.
10. Install the gasket and the purging bolt, and
then tighten the bolt to the specified torque.
WARNING
EWB02380Never run the engine in an enclosed area when
purging the spark arrester, otherwise it could
cause injury to the eyes, burns, carbon monox-
ide poisoning, possibly leading to death, and
start a fire.Always let the exhaust system cool prior to
touching exhaust components.Always wear eye protection, and make sure
no one is behind the ATV.Make sure there are no combustible materi-
als in the area.EBU26811Adjusting the engine idling speed The engine idling speed must be checked and, if
necessary, adjusted as follows at the intervals
specified in the periodic maintenance and lubrica-
tion chart.
1. Purging bolt
2. Gasket
1
2
Tightening torque:
Purging bolt:
27 Nm (2.7 m·kgf, 20 ft·lbf)
U1AS61E0.book Page 26 Thursday, February 11, 2010 2:17 PM
Page 114 of 154

8-27
8
TIPA diagnostic tachometer is needed to make this
adjustment.1. Start the engine and warm it up.
2. Attach the tachometer to the spark plug lead.
3. Check the engine idling speed and, if neces-
sary, adjust it to specification by turning the
idle adjusting screw. To increase the engine
idling speed, turn the idle adjusting screw in
direction (a), and to decrease it, turn the screw
in direction (b).
TIPIf the specified idling speed cannot be obtained as
described above, have a Yamaha dealer make the
adjustment.EBU24045Adjusting the throttle cable free play The throttle cable free play should be checked
and, if necessary, adjusted at the intervals speci-
fied in the periodic maintenance and lubrication
chart.
The throttle cable free play should measure 2.0–
4.0 mm (0.08–0.16 in) at the throttle lever. Period-
ically check the throttle cable free play and, if nec-
essary, adjust it as follows.TIPThe engine idling speed must be checked, and ad-
justed if necessary, before adjusting the throttle ca-
ble free play.1. Slide the rubber cover back.
2. Loosen the locknut.
1. Idle adjusting screw
1
(a)
(b)
Engine idling speed:
1500–1700 r/min
U1AS61E0.book Page 27 Thursday, February 11, 2010 2:17 PM