2021 YAMAHA YZF-R125 cooling

For your safety – pre-operation checks
4-1
4
EAU1559B
Inspect your vehicle each time you use it to make sure the vehicle is in safe operating 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 damag e.
Do not operate the vehicle if you fin d any pro blem. If a pro blem cannot be corrected 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 CHECKS PAGE
Fuel • Check fuel level in fuel tank.
• Refuel if necessary.
• Check fuel line for leakage.
• Check fuel tank breather hose and overflow hose for obstructions, cracks or
damage, and check hose connections. 3-16, 3-18
En gine oil • Check oil level in engine.
• If necessary, add recommended oil to specified level.
• Check vehicle for oil leakage. 6-11
Coolant • Check coolant level in reservoir.
• If necessary, add recommended coolant to specified level.
• Check cooling system for leakage. 6-14
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. 6-22, 6-23
UB5GE2E0.book Page 1 Thursday, July 30, 2020 3:08 PM

Periodic maintenance an d a djustment
6-37
6
EAU86420
En gine overheatin g
WARNING
EWAT1041
Do not remove the ra diator cap when the en gine an d ra diator are hot. Scal din g hot flui d an d steam may be
b lown 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 ra diator cap, an d then slowly rotate the cap counterclockwise to the
d etent to allow any resi dual pressure to escape. When the hissin g soun d has stoppe d, press down on the cap
while turnin g it counterclockwise, an d then remove the cap.TIPIf coolant is not available, tap water can be temporarily used instead, provided that it is changed to the recommended cool-
ant as soon as possible.
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 checkand 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.
UB5GE2E0.book Page 37 Thursday, July 30, 2020 3:08 PM

Specifications
8-1
8
Dimensions:Overall length:1990 mm (78.3 in)
Overall width:
755 mm (29.7 in)
Overall height: 1140 mm (44.9 in)
Seat height: 820 mm (32.3 in)
Wheelbase:
1325 mm (52.2 in)
Ground clearance: 160 mm (6.30 in)
Minimum turning radius: 2.9 m (9.51 ft)Wei ght:Curb weight:
144 kg (319 lb)Engine:Combustion cycle:
4-stroke
Cooling system: Liquid cooled
Valve train: SOHC
Number of cylinders:
Single cylinder
Displacement: 124 cm³
Bore × stroke:
52.0 × 58.6 mm (2.05 × 2.31 in)
Starting system:
Electric starter
Engine oil:Recommended brand:
SAE viscosity grades:
10W-40
Recommended engine oil grade: API service SG type or higher, JASO
standard MA
Engine oil quantity: Oil change: 0.85 L (0.90 US qt, 0.75 Imp.qt)
With oil filter removal: 0.95 L (1.00 US qt, 0.84 Imp.qt)Coolant quantity:Coolant reservoir (up to the maximum level
mark):
0.15 L (0.16 US qt, 0.13 Imp.qt)
Radiator (including all routes): 0.49 L (0.52 US qt, 0.43 Imp.qt)Fuel:Recommended fuel:
Unleaded gasoline (E10 acceptable)
Octane number (RON): 95
Fuel tank capacity: 11 L (2.9 US gal, 2.4 Imp.gal)
Fuel reserve amount:
3.0 L (0.79 US gal, 0.66 Imp.gal)
Fuel injection:Throttle body:ID mark: BK71 00Drivetrain:Gear ratio:
1st:2.833 (34/12)
2nd:
1.875 (30/16)
3rd: 1.364 (30/22)
4th: 1.143 (24/21)
5th:
0.957 (22/23)
6th: 0.840 (21/25)Front tire:Type:
Tubeless
Size: 100/80-17M/C 52S
Manufacturer/model: MICHELIN PILOT STREETRear tire:Type:Tubeless
Size: 140/70-17M/C 66S
Manufacturer/model:
MICHELIN PILOT STREET
UB5GE2E0.book Page 1 Thursday, July 30, 2020 3:08 PM