2019 YAMAHA YFZ450 radiator

4-2
4
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 8-53 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.EBU29943Engine 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-diagnosis system.
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8-20
8
EBU23472CoolantThe coolant level should be checked regularly. In
addition, the coolant must be changed at the in-
tervals specified in the periodic maintenance and
lubrication chart.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. EBU27946To check the coolant level1. Park the ATV on a level surface.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.
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)
UBW262E0.book Page 20 Tuesday, April 3, 2018 10:59 AM

8-21
83. 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] 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]
EBU2680A
Cleaning the air filter elementThe 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 rid-
ing 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.
1. Coolant reservoir cap
2. Maximum level mark
3. Minimum level mark
1
2
3
UBW262E0.book Page 21 Tuesday, April 3, 2018 10:59 AM

8-53
8Engine 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.
UBW262E0.book Page 53 Tuesday, April 3, 2018 10:59 AM

10-2
10
Starting system:Electric starter
Lubrication system: Dry sumpEngine oil:Recommended brand:YAMALUBE
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 only
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:1TD1 00Spark plug (s):Manufacturer/model:
NGK/CR8E
Spark plug gap: 0.7–0.8 mm (0.028–0.031 in)Drivetrain:Primary reduction ratio:
2.652 (61/23)
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
UBW262E0.book Page 2 Tuesday, April 3, 2018 10:59 AM