Yamaha YZ125 2021 - Changing the Coolant; Checking the Coolant Level; Checking the Cooling System

ENGINE
3-11
EAM30210
CHECKING THE COOLANT LEVEL
WARNING
EWA13030
A hot radiator is under pressure. Therefore,
do not remove the radiator cap when the en-
gine is hot. Scalding hot fluid and steam may
be blown out, which could cause serious in-
jury. When the engine has cooled, open the
radiator cap as follows:
Place a thick rag or a towel over the radiator
cap and slowly turn the radiator cap counter-
clockwise toward the detent to allow any re-
sidual pressure to escape. When the hissing
sound has stopped, press down on the radi-
ator cap and turn it counterclockwise to re-
move.
1. Stand the vehicle upright on a level surface.
2. Remove:
• Radiator cap “1”
3. Check:
• Coolant level
Maximum level “a” or below  Add coolant
up to the maximum level.
NOTICE
ECA24260
• Adding water instead of coolant lowers the
antifreeze content. If, therefore, water is
used instead of coolant, check, and if nec-
essary, adjust the antifreeze concentration.
• Use only distilled water. However, if dis-
tilled water is not available, soft water may
be used.
4. Start the engine, warm this up for several
minutes, and then stop it.
5. Check:
• Coolant level
TIP
Before checking the coolant level, wait a few
minutes until the coolant has settled.
EAM30211
CHECKING THE COOLING SYSTEM
1. Remove:
• Seat
• Side cover (left/right)
• Air scoop (left/right)
Refer to “GENERAL CHASSIS” on page 4-1.
2. Check:
• Radiator
• Radiator hose
Crack/damage  Replace.
Refer to “RADIATOR” on page 6-2.
3. Install:
• Air scoop (left/right)
• Seat
• Side cover (left/right)
Refer to “GENERAL CHASSIS” on page 4-1.
EAM30212
CHANGING THE COOLANT
WARNING
EWA13030
A hot radiator is under pressure. Therefore,
do not remove the radiator cap when the en-
gine is hot. Scalding hot fluid and steam may
be blown out, which could cause serious in-
jury. When the engine has cooled, open the
radiator cap as follows:
Place a thick rag or a towel over the radiator
cap and slowly turn the radiator cap counter-
clockwise toward the detent to allow any re-
sidual pressure to escape. When the hissing
sound has stopped, press down on the radi-
ator cap and turn it counterclockwise to re-
move.
1. Place a container under the engine.
2. Remove:
• Coolant drain bolt “1”
1. Radiator