2008 YAMAHA YZF-R125 engine

PERIODIC MAINTENANCE AND MINOR REPAIR
6-32
6
EAUM2200
Replacing the license plate
light bulb 1. Remove the socket (together with
the bulb) by pulling it out.
2. Remove the defective bulb by pull-
ing it out.
3. Insert a new bulb into the socket.
4. Install the socket (together with the
bulb) by pushing it in.
EAU43230
Replacing an auxiliary light
bulb This model is equipped with two auxil-
iary lights. If an auxiliary light bulb burns
out, replace it as follows.
1. Remove the socket (together with
the bulb) by pulling it out.
2. Remove the defective bulb by pull-
ing it out.
3. Insert a new bulb into the socket.
4. Install the socket (together with the
bulb) by pushing it in.
EAU24350
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 up-
right. Check that the motorcycle is in a
stable and level position before starting
any maintenance. A strong wooden
box can be placed under the engine for
added stability.
To service the front wheel
1. Stabilize the rear of the motorcycle
by using a motorcycle stand or, if
an additional motorcycle stand is
not available, by placing a jack un-
der the frame in front of the rear
wheel.
2. Raise the front wheel off the
ground by using a motorcycle
stand.
To service the rear wheel
Raise the rear wheel off the ground by
using a motorcycle stand or, if a motor-
cycle stand is not available, by placing
1. License plate light bulb
1. Auxiliary light bulb
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PERIODIC MAINTENANCE AND MINOR REPAIR
6-37
6
EAUM2440
Troubleshooting charts Starting problems or poor engine performance
WARNING
EWA10840
Keep away open flames and do not smoke while checking or working on the fuel system.
Check the fuel level in
the fuel tank.1. Fuel
There is enough fuel.
There is no fuel.
Check the compression.
Supply fuel.
Operate the electric starter.2. Compression
There is compression.
There is no compression.
Check the ignition.
Have a Yamaha dealer
check the vehicle.
Remove the spark plug
and check the electrodes.3. Ignition
Wet
Dry
Wipe off with a dry cloth and correct the
spark plug gap, or replace the spark plug.
Have a Yamaha dealer check the vehicle.The engine does not start.
Check the battery.
Operate the electric starter.
Operate the electric starter.4. Battery
The engine turns over
quickly.
The engine turns over
slowly.The battery is good.
Check the electrolyte and battery
lead connections, and charge the
battery if necessary.The engine does not start.
Have a Yamaha dealer
check the vehicle.
The engine does not start.
Check the compression.
U5D7E0E0.book Page 37 Tuesday, December 18, 2007 10:13 AM

PERIODIC MAINTENANCE AND MINOR REPAIR
6-38
6Engine overheating
WARNING
EWA10400


Do not remove the radiator cap when the engine and radiator are hot. Scalding hot fluid and steam may be
blown out under pressure, which could cause serious injury. Be sure to wait until the engine has cooled.


After removing the radiator cap retaining bolt, place a thick rag, like a towel, over the radiator cap, and then
slowly rotate the cap counterclockwise to the detent to allow any residual pressure to escape. When the hissingsound has stopped, press down on the cap while turning it counterclockwise, and then remove the cap.
NOTE:If coolant is not available, tap water can be temporarily used instead, provided that it is changed to the recommended coolantas 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 NOTE.)
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.
U5D7E0E0.book Page 38 Tuesday, December 18, 2007 10:13 AM

MOTORCYCLE CARE AND STORAGE
7-1
7
EAU37833
Matte color caution CAUTION:
ECA15192
Some models are equipped with
matte colored finished parts. Be
sure to consult a Yamaha dealer for
advice on what products to use be-
fore cleaning the vehicle. Using a
brush, harsh chemical products or
cleaning compounds when cleaning
these parts will scratch or damage
their surface. Wax also should not
be applied to any matte colored fin-ished parts.
EAUM2450
Care While the open design of a motorcycle
reveals the attractiveness of the tech-
nology, it also makes it more vulnera-
ble. Rust and corrosion can develop
even if high-quality components are
used. A rusty exhaust pipe may go un-
noticed on a car, however, it detracts
from the overall appearance of a motor-
cycle. Frequent and proper care does
not only comply with the terms of the
warranty, but it will also keep your
motorcycle looking good, extend its life
and optimize its performance.
Before cleaning
1. Cover the muffler outlet with a
plastic bag after the engine has
cooled down.
2. Make sure that all caps and covers
as well as all electrical couplers
and connectors, including the
spark plug cap, are tightly in-
stalled.
3. Remove extremely stubborn dirt,
like oil burnt onto the crankcase,
with a degreasing agent and a
brush, but never apply such prod-ucts onto seals, gaskets, sprock-
ets, the drive chain and wheel
axles. Always rinse the dirt and de-
greaser off with water.
Cleaning
CAUTION:
ECA10771


Avoid using strong acidic wheel
cleaners, especially on spoked
wheels. If such products are
used on hard-to-remove dirt, do
not leave the cleaner on the af-
fected area any longer than in-
structed. Also, thoroughly rinse
the area off with water, immedi-
ately dry it, and then apply a cor-
rosion protection spray.


Improper cleaning can damage
plastic parts such as cowlings,
panels, windshields, headlight
lenses, meter lenses, etc. Use
only a soft, clean cloth or
sponge with mild detergent and
water to clean plastic.


Do not use any harsh chemical
products on plastic parts. Be
sure to avoid using cloths or
sponges which have been in
U5D7E0E0.book Page 1 Tuesday, December 18, 2007 10:13 AM

MOTORCYCLE CARE AND STORAGE
7-2
7contact with strong or abrasive
cleaning products, solvent or
thinner, fuel (gasoline), rust re-
movers or inhibitors, brake flu-
id, antifreeze or electrolyte.


Do not use high-pressure wash-
ers or steam-jet cleaners since
they cause water seepage and
deterioration in the following ar-
eas: seals (of wheel and swing-
arm bearings, fork and brakes),
electric components (couplers,
connectors, instruments,
switches and lights), breather
hoses and vents.


For motorcycles equipped with
a windshield: Do not use strong
cleaners or hard sponges as
they will cause dulling or
scratching. Some cleaning com-
pounds for plastic may leave
scratches on the windshield.
Test the product on a small hid-
den part of the windshield to
make sure that it does not leave
any marks. If the windshield isscratched, use a quality plastic
polishing compound after
washing.
After normal use
Remove dirt with warm water, a mild
detergent, and a soft, clean sponge,
and then rinse thoroughly with clean
water. Use a toothbrush or bottlebrush
for hard-to-reach areas. Stubborn dirt
and insects will come off more easily if
the area is covered with a wet cloth for
a few minutes before cleaning. Use the
special sponge, which is located under
the tool kit, to clean the muffler and to
remove any discoloration from it.
After riding in the rain, near the sea oron salt-sprayed roadsSince sea salt or salt sprayed on roads
during winter are extremely corrosive in
combination with water, carry out the
following steps after each ride in the
rain, near the sea or on salt-sprayed
roads.
NOTE:Salt sprayed on roads in the winter mayremain well into spring.
1. Clean the motorcycle with cold wa-
ter and a mild detergent, after the
engine has cooled down.CAUTION:
ECA10790
Do not use warm water since it in-
creases the corrosive action of thesalt.
2. After drying the motorcycle, apply
a corrosion protection spray on all
metal, including chrome- and nick-
el-plated, surfaces to prevent cor-
rosion.
After cleaning
1. Dry the motorcycle with a chamois
or an absorbing cloth.
2. Immediately dry the drive chain
and lubricate it to prevent it from
rusting.
3. Use a chrome polish to shine
chrome, aluminum and stainless-
steel parts, including the exhaust
system. (Even the thermally in-
U5D7E0E0.book Page 2 Tuesday, December 18, 2007 10:13 AM

MOTORCYCLE CARE AND STORAGE
7-4
73. Perform the following steps to pro-
tect the cylinder, piston rings, etc.
from corrosion.
a. Remove the spark plug cap
and spark plug.
b. Pour a teaspoonful of engine oil
into the spark plug bore.
c. Install the spark plug cap onto
the spark plug, and then place
the spark plug on the cylinder
head so that the electrodes are
grounded. (This will limit spark-
ing during the next step.)
d. Turn the engine over several
times with the starter. (This will
coat the cylinder wall with oil.)
e. Remove the spark plug cap
from the spark plug, and then
install the spark plug and the
spark plug cap.
WARNING
EWA10950
To prevent damage or injury from
sparking, make sure to ground the
spark plug electrodes while turningthe engine over.4. Lubricate all control cables and the
pivoting points of all levers and
pedals as well as of the side-
stand/centerstand.
5. Check and, if necessary, correct
the tire air pressure, and then lift
the motorcycle so that both of its
wheels are off the ground. Alterna-
tively, turn the wheels a little every
month in order to prevent the tires
from becoming degraded in one
spot.
6. Cover the muffler outlet with a
plastic bag to prevent moisture
from entering it.
7. Remove the battery and fully
charge it. Store it in a cool, dry
place and charge it once a month.
Do not store the battery in an ex-
cessively cold or warm place [less
than 0 °C (30 °F) or more than 30
°C (90 °F)]. For more information
on storing the battery, see page
6-29.
NOTE:Make any necessary repairs beforestoring the motorcycle.
U5D7E0E0.book Page 4 Tuesday, December 18, 2007 10:13 AM

SPECIFICATIONS
8-1
8
Dimensions:Overall length:
2015 mm (79.3 in)
Overall width:
660 mm (26.0 in)
Overall height:
1065 mm (41.9 in)
Seat height:
818 mm (32.2 in)
Wheelbase:
1355 mm (53.3 in)
Ground clearance:
155 mm (6.10 in)
Minimum turning radius:
3100 mm (122.0 in)Weight:With oil and fuel:
138.0 kg (304 lb)Engine:Engine type:
Liquid cooled 4-stroke, SOHC
Cylinder arrangement:
Forward-inclined single cylinder
Displacement:
124.7 cm³
Bore × stroke:
52.0 × 58.6 mm (2.05 × 2.31 in)
Compression ratio:
11.20 :1
Starting system:
Electric starter
Lubrication system:
Wet sump
Engine oil:Type:
SAE 10W-30, SAE 10W-40, SAE 15W-40,
SAE 20W-40 or SAE 20W-50
Recommended engine oil grade:
API service SG type or higher, JASO
standard MA
Engine oil quantity:
Without oil filter element replacement:
0.95 L (1.00 US qt) (0.84 Imp.qt)
With oil filter element replacement:
1.00 L (1.06 US qt) (0.88 Imp.qt)Cooling system:Coolant reservoir capacity (up to the
maximum level mark):
0.25 L (0.26 US qt) (0.22 Imp.qt)
Radiator capacity (including all routes):
1.00 L (1.06 US qt) (0.88 Imp.qt)Air filter:Air filter element:
Dry element
Fuel:Recommended fuel:
Premium unleaded gasoline only
Fuel tank capacity:
13.8 L (3.65 US gal) (3.04 Imp.gal)
Fuel reserve amount:
1.6 L (0.42 US gal) (0.35 Imp.gal)Fuel injection:Throttle body:
Manufacturer:
MIKUNI
Type/quantity:
SE AC28-2/1Spark plug (s):Manufacturer/model:
NGK/CR8E
Spark plug gap:
0.7–0.8 mm (0.028–0.031 in)Clutch:Clutch type:
Wet, multiple-discTransmission:Primary reduction system:
Helical gear
Primary reduction ratio:
73/24 (3.042)
Secondary reduction system:
Chain drive
Secondary reduction ratio:
48/14 (3.429)
Transmission type:
Constant mesh 6-speed
Operation:
Left foot operation
-20 -10 0
10 20 30
40
50 ˚C
SAE 10W-30
SAE 15W-40SAE 20W-40SAE 20W-50
SAE 10W-40SAE 10W-50
U5D7E0E0.book Page 1 Tuesday, December 18, 2007 10:13 AM

SPECIFICATIONS
8-3
8
Battery:Model:
12N5.5-3B / YUASA
Voltage, capacity:
12 V, 5.5 AhHeadlight:Bulb type:
Halogen bulbBulb voltage, wattage × quantity:Headlight:
12 V, 55.0 W × 2
Tail/brake light:
LEDS x 8
Front turn signal light:
12 V, 10.0 W × 2
Rear turn signal light:
12 V, 10.0 W × 2
Auxiliary light:
12 V, 5.0 W × 2
Meter lighting:
LED
Neutral indicator light:
LED
High beam indicator light:
LED
Turn signal indicator light:
LED
Coolant temperature warning light:
LED
Engine trouble warning light:
LEDFuses:Main fuse:
20.0 AHeadlight fuse:
15.0 A
Signaling system fuse:
7.5 A
Ignition fuse:
7.5 A
Radiator fan fuse:
5.0 A
U5D7E0E0.book Page 3 Tuesday, December 18, 2007 10:13 AM