2010 YAMAHA YBR125 engine

PERIODIC MAINTENANCE AND ADJUSTMENT
6-7
6
EAU36961
Panel B
To remove the panel1. Slide the panel lock cover open, in-
sert the key into the lock, and then
turn it 1/4 turn clockwise.
2. Pull the front of the panel out with
the key inserted in the lock, and
then slide the panel forward to re-
lease it in the rear.To install the panel
1. Secure the rear of the panel, and
then push the front of the panel in
with the key inserted in the lock.
2. While pushing the panel inward,
turn the key counterclockwise to
the original position, remove it, and
then close the panel lock cover.
EAU19604
Checking the spark plug The spark plug is an important engine
component, which is easy to check.
Since heat and deposits will cause any
spark plug to slowly erode, the spark
plug should be removed and checked
in accordance with the periodic mainte-
nance and lubrication chart. In addition,
the condition of the spark plug can re-
veal the condition of the engine.
To remove the spark plug
1. Remove the spark plug cap.
2. Remove the spark plug as shown,
with the spark plug wrench includ-
ed in the owner’s tool kit.
1. Panel lock cover
2. Unlock.
1
2
1. Spark plug cap
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PERIODIC MAINTENANCE AND ADJUSTMENT
6-8
6To check the spark plug
1. Check that the porcelain insulator
around the center electrode of the
spark plug is a medium-to-light tan
(the ideal color when the vehicle is
ridden normally).
TIPIf the spark plug shows a distinctly dif-
ferent color, the engine could be oper-
ating improperly. Do not attempt to
diagnose such problems yourself. In-
stead, have a Yamaha dealer check
the vehicle.
2. Check the spark plug for electrode
erosion and excessive carbon or
other deposits, and replace it if
necessary.
3. Measure the spark plug gap with a
wire thickness gauge and, if nec-
essary, adjust the gap to specifica-
tion.To install the spark plug
1. Clean the surface of the spark plug
gasket and its mating surface, and
then wipe off any grime from the
spark plug threads.
2. Install the spark plug with the
spark plug wrench, and then tight-
en it to the specified torque.
TIPIf a torque wrench is not available when
installing a spark plug, a good estimate
of the correct torque is 1/4–1/2 turn
past finger tight. However, the spark
plug should be tightened to the speci-
fied torque as soon as possible.3. Install the spark plug cap.
1. Spark plug wrench
Specified spark plug:
NGK/CR6HSA1. Spark plug gapSpark plug gap:
0.6–0.7 mm (0.024–0.028 in)
Tightening torque:
Spark plug:
13 Nm (1.3 m·kgf, 9.4 ft·lbf)
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PERIODIC MAINTENANCE AND ADJUSTMENT
6-9
6
EAU37173
Engine oil The engine oil level should be checked
before each ride. In addition, the oil
must be changed at the intervals spec-
ified in the periodic maintenance and
lubrication chart.
To check the engine oil level
1. Place the vehicle on the center-
stand. A slight tilt to the side can
result in a false reading.
2. Start the engine, warm it up for
several minutes, and then turn it
off.
3. Wait a few minutes until the oil set-
tles, remove the oil filler cap, wipe
the dipstick clean, insert it back
into the oil filler hole (without
screwing it in), and then remove it
again to check the oil level.
TIPThe engine oil should be between the
minimum and maximum level marks.
4. If the engine oil is at or below the
minimum level mark, add sufficient
oil of the recommended type to
raise it to the correct level.
5. Insert the dipstick into the oil filler
hole, and then tighten the oil filler
cap.
To change the engine oil
1. Start the engine, warm it up for
several minutes, and then turn it
off.
2. Place an oil pan under the engine
to collect the used oil.
3. Remove the engine oil filler cap,
the engine oil drain bolt and its
gasket to drain the oil from the
crankcase.
1. Engine oil filler cap
1. Engine oil dipstick
2. Maximum level mark
3. Minimum level mark
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PERIODIC MAINTENANCE AND ADJUSTMENT
6-10
64. Install the engine oil drain bolt and
its new gasket, and then tighten
the bolt to the specified torque.
5. Refill with the specified amount of
the recommended engine oil, and
then install and tighten the engine
oil filler cap.
NOTICE
ECA11620


In order to prevent clutch slip-
page (since the engine oil also
lubricates the clutch), do not
mix any chemical additives. Do
not use oils with a diesel speci-
fication of “CD” or oils of a high-
er quality than specified. In
addition, do not use oils labeled
“ENERGY CONSERVING II” or
higher.


Make sure that no foreign mate-
rial enters the crankcase.
6. Start the engine, and then let it idle
for several minutes while checking
it for oil leakage. If oil is leaking, im-
mediately turn the engine off and
check for the cause.
7. Turn the engine off, wait a few min-
utes until the oil settles, and then
check the oil level and correct it if
necessary.
EAU37123
Cleaning the air filter element The air filter element should be cleaned
at the intervals specified in the periodic
maintenance and lubrication chart.
Clean or, if necessary, replace the air
filter element more frequently if you are
riding in unusually wet or dusty areas.
1. Remove panel A. (See page 6-6.)
2. Remove the air filter case cover by
removing the screws.
3. Remove the air filter element.
1. Engine oil drain bolt
2. Gasket
3. Oil panTightening torque:
Engine oil drain bolt:
20 Nm (2.0 m·kgf, 14 ft·lbf)
Recommended engine oil:
See page 8-1.
Oil change quantity:
1.00 L (1.06 US qt, 0.88 Imp.qt)
1
3
2
1. Screw
2. Air filter case cover
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PERIODIC MAINTENANCE AND ADJUSTMENT
6-11
6 4. Remove the sponge material from
the air filter element.
5. Lightly tap the air filter element to
remove most of the dust and dirt,
and then blow the remaining dirt
out with compressed air on the
mesh side as shown. If the air filter
element is damaged, replace it.6. Clean the sponge material with
solvent, then squeeze the remain-
ing solvent out, and be sure to let
the sponge material dry before in-
stalling it into the air filter element.
If the sponge material is damaged,
replace it. WARNING! Use only a
dedicated parts cleaning sol-
vent. To avoid the risk of fire or
explosion, do not use gasoline
or solvents with a low flash
point.
[EWA10431]
NOTICE: To avoid
damaging the sponge material,
handle it gently and carefully,
and do not twist it.
[ECA15101]
7. Install the sponge material into the
air filter element, and then install
the air filter element into the air fil-
ter case. NOTICE: Make sure that
the air filter element is properly
seated in the air filter case. The
engine should never be operat-
ed without the air filter element
installed, otherwise the pis-
ton(s) and/or cylinder(s) may
become excessively worn.
[ECA10481]
8. Install the air filter case cover by in-
stalling the screws.
9. Check the hose at the bottom of
the air filter case for accumulated
dust or water, and if necessary,
drain it by removing the clamp, and
then removing the plug.
1. Sponge material
2. Air filter element
1. Air filter element
1
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PERIODIC MAINTENANCE AND ADJUSTMENT
6-12
610. Install the plug into the check
hose, and then install the clamp.
11. Install the panel.
EAU44734
Checking the engine idling
speed Check the engine idling speed and, if
necessary, have it corrected by a
Yamaha dealer.
EAU21383
Checking the throttle cable
free play The throttle cable free play should mea-
sure 3.0–7.0 mm (0.12–0.28 in) at the
inner edge of the throttle grip. Periodi-
cally check the throttle cable free play
and, if necessary, have a Yamaha deal-
er adjust it.
1. Clamp
2. Air filter check hose plug
Engine idling speed:
1300–1500 r/min
1. Throttle cable free play
1
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PERIODIC MAINTENANCE AND ADJUSTMENT
6-13
6
EAU21401
Valve clearance The valve clearance changes with use,
resulting in improper air-fuel mixture
and/or engine noise. To prevent this
from occurring, the valve clearance
must be adjusted by a Yamaha dealer
at the intervals specified in the periodic
maintenance and lubrication chart.
EAU21562
Tires To maximize the performance, durabil-
ity, and safe operation of your motorcy-
cle, note the following points regarding
the specified tires.
Tire air pressure
The tire air pressure should be checked
and, if necessary, adjusted before each
ride.
WARNING
EWA10501
Operation of this vehicle with im-
proper tire pressure may cause se-
vere injury or death from loss of
control.

The tire air pressure must be
checked and adjusted on cold
tires (i.e., when the temperature
of the tires equals the ambient
temperature).


The tire air pressure must be ad-
justed in accordance with the
riding speed and with the total
weight of rider, passenger, car-
go, and accessories approved
for this model.
WARNING
EWA10511
Never overload your vehicle. Opera-
tion of an overloaded vehicle could
cause an accident.
Tire air pressure (measured on cold
tires):
0–90 kg (0–198 lb):
Fr o nt :
175 kPa (1.75 kgf/cm², 25 psi)
Rear:
200 kPa (2.00 kgf/cm², 29 psi)
90–153 kg (198–337 lb):
Fr o nt :
175 kPa (1.75 kgf/cm², 25 psi)
Rear:
280 kPa (2.80 kgf/cm², 41 psi)
Maximum load*:
153 kg (337 lb)
* Total weight of rider, passenger, car-
go and accessories
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PERIODIC MAINTENANCE AND ADJUSTMENT
6-22
6
EAU23025
Cleaning and lubricating the
drive chain The drive chain must be cleaned and
lubricated at the intervals specified in
the periodic maintenance and lubrica-
tion chart, otherwise it will quickly wear
out, especially when riding in dusty or
wet areas. Service the drive chain as
follows.NOTICE
ECA10583
The drive chain must be lubricated
after washing the motorcycle, riding
in the rain or riding in wet areas.1. Clean the drive chain with kero-
sene and a small soft brush.
NOTICE: To prevent damaging
the O-rings, do not clean the
drive chain with steam cleaners,
high-pressure washers or inap-
propriate solvents.
[ECA11121]
2. Wipe the drive chain dry.
3. Thoroughly lubricate the drive
chain with a special O-ring chain
lubricant. NOTICE: Do not use
engine oil or any other lubri-
cants for the drive chain, as theymay contain substances that
could damage the O-rings.
[ECA11111]EAU23101
Checking and lubricating the
cables The operation of all control cables and
the condition of the cables should be
checked before each ride, and the ca-
bles and cable ends should be lubricat-
ed if necessary. If a cable is damaged
or does not move smoothly, have a
Yamaha dealer check or replace it.
WARNING! Damage to the outer
sheath may interfere with proper ca-
ble operation and will cause the in-
ner cable to rust. Replace a
damaged cable as soon as possible
to prevent unsafe conditions.
[EWA10721]
Recommended lubricant:
Engine oil
U51DE0E0.book Page 22 Monday, November 2, 2009 10:34 AM