Yamaha YZF-R125 Service Manual: Checking and charging the battery
WARNING Batteries generate explosive hydrogen gas
and contain electrolyte which is made of poisonous
and highly caustic sulfuric acid.
Therefore, always follow these preventive
measures:
- Wear protective eye gear when handling or
working near batteries.
- Charge batteries in a well-ventilated area.
- Keep batteries away from fire, sparks or
open flames (e.g., welding equipment,
lighted cigarettes).
- DO NOT SMOKE when charging or handling
batteries.
- KEEP BATTERIES AND ELECTROLYTE
OUT OF REACH OF CHILDREN.
- Avoid bodily contact with electrolyte as it
can cause severe burns or permanent eye
injury.
FIRST AID IN CASE OF BODILY CONTACT:
EXTERNAL
- Skin - Wash with water.
- Eyes - Flush with water for 15 minutes and
get immediate medical attention.
INTERNAL
- Drink large quantities of water or milk followed
with milk of magnesia, beaten egg or
vegetable oil. Get immediate medical attention.
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1. Remove:
- Rider seat
Refer to "GENERAL CHASSIS" on page 4-1.
2. Disconnect:
- Battery leads
(from the battery terminals)
CAUTION: First, disconnect the negative battery
lead
"1", then the positive battery lead "2". |

3. Remove:
4. Check:
CAUTION: Add only distilled water. Tap water contains
minerals which are harmful to the battery. |
5. Check:
- Specific gravity
Less than 1.280
Recharge the
battery. 
6. Charge:
Battery charging amperage and time
5.5 amps/10 hrs
WARNING
Do not quick charge a battery.
CAUTION:
- Loosen the battery sealing caps.
- Make sure the battery breather hose and
battery vent are free of obstructions.
- To ensure maximum performance, always
charge a new battery before using it.
- Do not use a high-rate battery charger.
They force a high-amperage current into
the battery quickly and can cause battery
overheating and battery plate damage.
- If it is impossible to regulate the charging
current on the battery charger, be careful
not to overcharge the battery.
- When charging a battery, be sure to remove
it from the vehicle. (If charging has to be
done with the battery mounted on the vehicle,
disconnect the negative lead from the
battery terminal.)
- To reduce the chance of sparks, do not
plug in the battery charger until the battery
charger leads are connected to the battery.
- Before removing the battery charger lead
clips from the battery terminals, be sure to
turn off the battery charger.
- Make sure the battery charger lead clips are
in full contact with the battery terminal and
that they are not shorted. A corroded battery
charger lead clip may generate heat in
the contact area and a weak clip spring may
cause sparks.
- If the battery becomes hot to the touch at
any time during the charging process, disconnect
the battery charger and let the battery
cool before reconnecting it. Hot
batteries can explode!
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NOTE:
- Replace the battery whenever:
- battery voltage does not rise to specification or
bubbles fail to rise during charging,
- sulphation of one or more battery cells occurs
(as indicated by the battery plates turning white
or material accumulating in the bottom of the
battery cell),
- specific gravity readings after a long, slow
charge indicate that one battery cell's charge is
lower than the rest,
- warpage or buckling of the battery plates or insulators
is evident.
7. Check:
Battery breather hose and battery vent
Obstruction → Clean.
Damage → Replace.
8. Install:
9. Connect:
- Battery breather hose "1"

CAUTION:
- When checking the battery, make sure the
battery breather hose is properly installed
and routed correctly. If the battery breather
hose is positioned so as to allow electrolyte
or hydrogen gas from the battery to contact
the frame, the vehicle and its finish may be
damaged.
- Make sure the battery breather hose is
properly routed away from the drive chain
and from below the swingarm.
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10.Check:
11.Connect:
- Battery leads
(to the battery terminals)
CAUTION: First, connect the positive battery lead
"1",
then the negative battery lead "2". |

12.Lubricate:
- Battery terminals
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13.Install:
- Rider seat
Refer to "GENERAL CHASSIS" on page 4-1.
The following procedure applies to all of the fuses.
CAUTION:To avoid a short circuit, always turn the
main
switch to "OFF" when checking or replacing
a fuse.
1. Remove:
Ri ...
Check each switch for continuity with the pocket
tester. If the continuity reading is incorrect, replace
the relay.
1. Disconnect the relay from the wire harness.
2. Connect the pocket tester ( ...
Other materials:
Checking the fuel sender
1. Drain the fuel from the fuel tank.
2. Check:
Fuel sender resistance
Out of specification → Replace the fuel
sender.
a. Connect the pocket tester ( ×
10) to the fuel
sender coupler as shown.
Positive tester probe
sky blue "1"
Negative tester probe
orange/white " ...
Supporting the motorcycle
Since this model is not equipped with a
centerstand, follow these precautions
when removing the front and rear
wheel or performing other maintenance
requiring the motorcycle to stand upright.
Check that the motorcycle is in a
stable and level position before starting
any maintenance. A ...
Genuine Yamaha Accessories
Choosing accessories for your vehicle
is an important decision. Genuine
Yamaha accessories, which are available
only from a Yamaha dealer, have
been designed, tested, and approved
by Yamaha for use on your vehicle.
Many companies with no connection to
Yamaha manufacture parts and access ...
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