2021 YAMAHA YFZ450R radiator

5-2
5
EBU29924Coolant temperature warning light “ ”
This warning light comes on when the engine
overheats. When this occurs, stop the engine as
soon as it is safe to do so and allow it to cool for
10 minutes.
The electrical circuit of the warning light can be
checked by turning the key to “ ” (on). The
warning light should come on for a few seconds,
and then go off.
If the warning light does not come on initially when
the key is turned to “ ” (on), or if the warning
light remains on, have a Yamaha dealer check the
vehicle.TIPThe radiator fan is automatically switched on or
off according to the coolant temperature in the
radiator.
 If the engine overheats, see page 9-53 for fur-
ther instructions. NOTICEECB00011The engine may overheat if the ATV is over-
loaded. In this case, reduce the load to spec-
ification. 
Start the engine after making sure that the
warning light is out. Continuous use while
the warning light is on may cause damage to
the engine.
EBU29933Fuel level warning light “ ”
This warning light comes on when the fuel level
drops below approximately 3.4 L (0.90 US gal,
0.75 Imp.gal). When this occurs, refuel as soon as
possible.
The electrical circuit of the warning light can be
checked by setting the engine stop switch to “ ”
and turning the key to “ ” (on). The warning light
should come on for a few seconds, and then go
off.
If the warning light does not come on initially when
the key is turned to “ ” (on), or if the warning
light remains on, have a Yamaha dealer check the
electrical circuit.EBU29944Engine trouble warning light “ ”
This warning light comes on or flashes when an
electrical circuit monitoring the engine is not work-
ing correctly. When this occurs, have a Yamaha
dealer check the self-diagnostic system.
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9
EBU38620Why YamalubeYAMALUBE oil is a Genuine YAMAHA Part born ofthe engineers’ passion and belief that engine oil is
an important liquid engine component. We form
teams of specialists in the fields of mechanical en-
gineering, chemistry, electronics and track test-
ing, and have them develop the engine together
with the oil it will use. Yamalube oils take full ad-
vantage of the base oil’s qualities and blend in the
ideal balance of additives to make sure the final oil
clears our performance standards. Thus,
Yamalube mineral, semisynthetic and synthetic oils have their own distinct characters and value.
Yamaha’s experience gained over many years of research and development into oil since the
1960’s helps make Yamalube the best choice for
your Yamaha engine.
EBU23473CoolantThe coolant level should be checked regularly. In
addition, the coolant must be changed at the in-
tervals specified in the periodic maintenance
chart.
Tightening torque:
Engine guard bolt:7 N·m (0.7 kgf·m, 5.2 lb·ft)Recommended coolant:YAMALUBE coolant
Coolant quantity: Coolant reservoir (up to full level):0.25 L (0.26 US qt, 0.22 Imp.qt)
Radiator (including all routes): 1.25 L (1.32 US qt, 1.10 Imp.qt)
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9
TIPIf genuine Yamaha coolant is not available, use an
ethylene glycol antifreeze containing corrosion in-
hibitors for aluminum engines and mix with dis-
tilled water at a 1:1 ratio. NOTICEECB02190Mix 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 en-
gine. EBU27947To check the coolant level1. Park the ATV on a level surface.
2. Wait for the engine to cool for an accurate reading.
3. Look at the coolant level in the coolant reser- voir. 4. If the coolant is at or below the minimum level
mark, remove the coolant reservoir cap.
WARNING! Remove only the coolant res-
ervoir cap. Never attempt to remove the
radiator cap when the engine is hot.
[EWB02672]
5. Add coolant to the maximum level mark, andthen 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 in-1. Coolant reservoir cap
2. Maximum level mark
3. Minimum level mark
1
2
3
UBKD60E0.book Page 21 Wednesday, November 18, 2020 8:39 AM

9-22
9
stead of coolant, replace it with coolant as
soon as possible, otherwise 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 effective-
ness of the coolant will be reduced.
[ECB01012]
EBU29863
Changing the coolant
The coolant must be changed at the intervals
specified in the periodic maintenance chart. Have
a Yamaha dealer change the coolant. WARNING!
Never attempt to remove the radiator cap
when the engine is hot.
[EWB04300]
EBU2680B
Cleaning the air filter elementThe air filter element should be cleaned at the in-
tervals specified in the periodic maintenance
chart. Clean or, if necessary, replace the air filter
element more frequently if you are riding in unusu-
ally 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. 1. Park the ATV on a level surface.
2. Remove the seat. (See page 5-10.)
3. Remove the air filter case cover by unhooking the holders.1. Air filter case check hose
1
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9-53
9Engine overheating
WARNING
EWB02291Wait for the engine and radiator to cool before removing the radiator cap. You could be burned by
hot fluid and steam blown out under pressure. Always put a thick rag over the cap when opening.
Allow any remaining pressure to escape before completely removing the cap. TIP
Tap water can be used in an emergency. Change to the recommended coolant as soon as possible.
 The engine will tend to overheat if the radiator is caked with mud, or if the ATV is overloaded. Wait until the
engine has cooled.
Check the coolant level in the
reservoir and radiator.
The coolant level
is OK.The coolant level is low.
Check the cooling system
for leakage.
Have a Yamaha dealer check
and repair the cooling system.Add coolant. (See TIP.)
Start the engine. If the engine overheats again, have a
Yamaha dealer check and repair the cooling system.
There is
leakage.
There is
no leakage.
UBKD60E0.book Page 53 Wednesday, November 18, 2020 8:39 AM

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Starting system:Electric starter
Lubrication system: Dry sumpEngine oil:Recommended brand:
SAE viscosity grades:
5W-30, 10W-30, 10W-40, 15W-40, 20W-40, 20W-50
Recommended engine oil grade: API service SG type or higher, JASO standard MA
Quantity: Oil change:1.40 L (1.48 US qt, 1.23 Imp.qt) With oil filter removal:
1.45 L (1.53 US qt, 1.28 Imp.qt)
Coolant quantity:Radiator (including all routes):
1.25 L (1.32 US qt, 1.10 Imp.qt)
Coolant reservoir (up to the maximum level mark): 0.25 L (0.26 US qt, 0.22 Imp.qt)Air filter:Air filter element:
Wet element
Air filter oil grade: Foam air-filter oilFuel:Recommended fuel:
Premium unleaded gasoline (Gasohol [E10] acceptable)
Minimum research octane: 97
Fuel tank capacity: 10 L (2.6 US gal, 2.2 Imp.gal)
Fuel reserve amount:
3.4 L (0.90 US gal, 0.75 Imp.gal)Throttle body:ID mark:1TD1Spark plug (s):Manufacturer/model:NGK/CR8E
Spark plug gap: 0.7–0.8 mm (0.028–0.031 in)
0 10 30 50 70 90 110 130 F
–20 –10 0 10 20 30 40 50 CSAE 5W-30
SAE 10W-30
SAE 10W-40
SAE 15W-40
SAE 20W-40SAE 20W-50
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