2021 YAMAHA YZ85 cooling

For your safety – pre-operation checks
5-1
5
EAU63441
Inspect your vehicle each time you use it to make sure the vehicle is in safe oper-
ating condition. Always follow the inspection and maintenance procedures and
schedules described in the Owner’s Manual.
WARNING
EWA11152
Failure to inspect or maintain the vehicle properly increases the possibility
of an acci dent or equipment d amage. Do not operate the vehicle if you fin d
any pro blem. If a pro blem cannot be correcte d b y the proce dures provi ded
in this manual, have the vehicle inspecte d b y a Yamaha dealer.
Before using this vehicle, check the following points:
ITEM CHECKSPAGE
Fuel • Check fuel level in fuel tank.
• Always use a fresh mixture of gasoline and oil.
• Check fuel line for leakage.
• Check fuel tank breather hose for obstructions, cracks
or damage, and check hose connection. 4-4, 4-6
Transmission oil • Check for leakage. 7-7
Coolant • Check coolant level.
• If necessary, add recommended coolant to specified
level.
• Check cooling system for leakage. 7-8
Front brake • Check operation.
• If soft or spongy, have Yamaha dealer bleed hydraulic
system.
• Check brake pads for wear.
• Replace if necessary.
• Check fluid level in reservoir.
• If necessary, add specified brake fluid to specified level.
• Check hydraulic system for leakage. 7-19,
7-20
Rear brake • Check operation.
• If soft or spongy, have Yamaha dealer bleed hydraulic
system.
• Check brake pads for wear.
• Replace if necessary.
• Check fluid level in reservoir.
• If necessary, add specified brake fluid to specified level.
• Check hydraulic system for leakage. 7-19,
7-20
Clutch • Check operation.
• Lubricate cable if necessary.
• Check lever free play.
• Adjust if necessary. 7-17
Throttle grip • Make sure that operation is smooth.
• Check throttle grip free play.
• If necessary, adjust throttle grip free play. 7-13,
7-24
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Periodic maintenance an d a djustment
7-4
7
23 *Front fork Check operation and for oil leakage.
Adjust if necessary.
 Clean dust seal and lubricate with
lithium-soap-based grease.
Replace fork oil.
 Replace oil seals.
NO. ITEM ROUTINE
After
break-in
Everyrace
Every
third race
Every
fifth race
As
required
Check coolant level and for leakage.
17 *
Cooling system Check hoses for cracks or damage. Check radiator cap spring operation. Change coolant.
Every 2 years
Every year Check all chassis fitting and fasteners.
18
*Chassis fasteners
Correct or tighten if necessary.
19Air filter element Clean. Replace.
20 *Frame Clean and check for damage.

21
*Fuel line Clean and check for leakage.
22 *
Brakes Adjust lever position and pedal height.
Lubricate pivot points.
Check brake disk surface.
Check fluid level and for leakage.
Tighten brake disk bolts, caliper bolts,
master cylinder bolts and union bolts.
Replace brake pads.
 Replace brake fluid.
UB4B82E0.book Page 4 Wednesday, March 11, 2020 1:10 PM

Periodic maintenance an d a djustment
7-9
7
TIP
The coolant should be at the bottom of
the radiator filler neck. The level will
change with variation of engine tem-
perature.
3. If the coolant is below the correct
coolant level, add coolant, and
then install the radiator cap.
NOTICE: If coolant is not avail-
a b le, use distille d water or soft
tap water instead . Do not use
har d water or salt water since it
is harmful to the en gine. If water
has been used instead of cool-
ant, replace it with coolant as
soon as possi ble, otherwise the
coolin g system will not be pro-
tected against frost an d corro-
sion. If water has b een added to
the coolant, have a Yamaha
d ealer check the antifreeze con-
tent of the coolant as soon as
possi ble, otherwise the effec-
tiveness of the coolant will be
re duce d.
[ECA10473]
EAUM1318
To change the coolant
1. Place the vehicle on a level sur- face and let the engine cool if nec-
essary. 2. Place a container under the en-
gine to collect the used coolant.
3. Remove the radiator cap, and then the coolant drain bolt and its
gasket to drain the cooling sys-
tem. WARNING! Never attempt
to remove the ra diator cap
when the en gine is hot.
[EWA10382]
4. After the coolant is completely
drained, thoroughly flush the cool-
ing system with clean tap water.
5. Install the coolant drain bolt and its new gasket, and then tighten
the bolt to the specified torque.
1. Correct coolant level
1
1. Radiator cap
1. Coolant drain bolt
2. Gasket
Tightenin g torque:
Coolant drain bolt: 10 N·m (1.0 kgf·m, 7.4 lb·ft)
1
21
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Periodic maintenance an d a djustment
7-10
7 6. Pour the recommended coolant
into the radiator until it is full.
7. Install the radiator cap, start the engine, let it idle for several min-
utes, and then turn it off.
8. Remove the radiator cap to check the coolant level in the radiator. If
necessary, add sufficient coolant
until it reaches the bottom of the
radiator filler neck, and then install
the radiator cap.
9. Start the engine, and then check the vehicle for coolant leakage. If
coolant is leaking, have a Yamaha
dealer check the cooling system.
EAU48393
Cleanin g the air filter element
The air filter element should be cleaned
or replaced at the intervals specified in
the periodic maintenance and lubrica-
tion chart. Clean or, if necessary, re-
place the air filter element more
frequently if you are riding in unusually
wet or dusty areas.
1. Remove the seat. (See page 4-8.)
2. Remove the air filter case cover as shown.
3. Remove the air filter element by removing the wing bolt and its
washer.
Antifreeze/water mixture ratio:1:1
Recommen ded antifreeze:
High-quality ethylene glycol anti-
freeze containing corrosion inhibi-
tors for aluminum engines
Coolant quantity:
Radiator (including all routes):0.55 L (0.58 US qt, 0.48 Imp.qt)
1. Air filter case cover
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Periodic maintenance an d a djustment
7-33
7
EAU86430En gine overheatin g
WARNING
EWAT1041
Do not remove the rad iator cap when the engine an d ra diator are hot.
Scal din g hot flui d an d steam may b e blown out un der pressure, which
coul d cause serious injury. Be sure to wait until the en gine has coole d.
 Place a thick ra g, like a towel, over the rad iator cap, and then slowly ro-
tate the cap counterclockwise to the d etent to allow any residual pres-
sure to escape. When the hissin g soun d has stopped , press down on the
cap while turnin g it counterclockwise, an d then remove the cap.
TIP
If coolant is not available, tap water can be temporarily used instead, provided
that it is changed to the recommended coolant as soon as possible.
Wait until the engine
has cooled.
Check the coolant
level in the reservoir
and radiator.Add coolant.
(See TIP.)
The coolant level is
OK.
There is no leakage.
There is leakage.
The coolant level is
low.
Check the cooling
system for leakage.
Have a Yamaha
dealer check and
repair the cooling
system.
Start the engine. If the engine overheats again,
have a Yamaha dealer check and repair the cooling
system.
UB4B82E0.book Page 33 Wednesday, March 11, 2020 1:10 PM

Specifications
9-1
9
Dimensions:
Overall length:1820 mm (71.7 in) (YZ85, YZ85M)
1895 mm (74.6 in) (YZ85LW, YZ85LWM)
Overall width: 760 mm (29.9 in)
Overall height:
1145 mm (45.1 in) (YZ85, YZ85M)
1175 mm (46.3 in) (YZ85LW, YZ85LWM)
Seat height:
840 mm (33.1 in) (YZ85, YZ85M)
870 mm (34.3 in) (YZ85LW, YZ85LWM)
Wheelbase:
1255 mm (49.4 in) (YZ85, YZ85M)
1285 mm (50.6 in) (YZ85LW, YZ85LWM)
Ground clearance: 330 mm (12.99 in) (YZ85, YZ85M)
360 mm (14.17 in) (YZ85LW, YZ85LWM)
Wei ght:
Curb weight:
73 kg (161 lb) (YZ85, YZ85M)
75 kg (165 lb) (YZ85LW, YZ85LWM)
Engine:
Combustion cycle:
2-stroke
Cooling system: Liquid cooled
Number of cylinders:
Single cylinder
Displacement: 85 cm³
Bore × stroke:
47.5 × 47.8 mm (1.87 × 1.88 in)
Starting system:
Kickstarter
Engine oil:
Engine oil:
YAMALUBE 2R
Recommended brand:
Transmission oil:
Type:
Motor oil SAE 10W-30 type SE or higher or
Gear oil SAE 85W GL-3
Quantity:
0.50 L (0.53 US qt, 0.44 Imp.qt)
Coolant quantity:
Radiator (including all routes): 0.55 L (0.58 US qt, 0.48 Imp.qt)
Fuel:
Recommended fuel:Unleaded gasoline (E10 acceptable)
Octane number (RON): 98
Fuel tank capacity:
5.0 L (1.3 US gal, 1.1 Imp.gal)
Car buretor:
Type × quantity:
PWK28 × 1
Drivetrain:
Gear ratio:
1st:
2.455 (27/11)
2nd:
1.882 (32/17)
3rd: 1.529 (26/17)
4th: 1.294 (22/17)
5th:
1.130 (26/23)
6th: 1.000 (25/25)
Front tire:
Type:
With tube
Size: 70/100-17 40M (YZ85, YZ85M)
70/100-19 42M (YZ85LW, YZ85LWM)
Manufacturer/model: DUNLOP/MX3SF
Rear tire:
Type:
With tube
Size: 90/100-14 49M (YZ85, YZ85M)
90/100-16 52M (YZ85LW, YZ85LWM)
Manufacturer/model: DUNLOP/MX3S
Front brake:
Type:
Hydraulic single disc brake
Rear brake:
Type:
Hydraulic single disc brake
UB4B82E0.book Page 1 Wednesday, March 11, 2020 1:10 PM