YAMAHA YZF-R125 2020 Workshop Manual

Periodic maintenance and adjustment
6-7
6
EAU18782
Removing and installing cowl-
ings
The cowlings shown need to be re-
moved to perform some of the mainte-
nance jobs described in this chapter.
Refer to this section each time a cowl-
ing needs to be removed and installed.
EAUM4041
Cowling A
To remove the cowling
Remove the quick fastener, screws
and bolt, and then take the cowling off.
TIP
The quick fastener is removed by
pushing the center pin in with a screw-
driver, then pulling the fastener out.
To install the cowling
Place the cowling in the original posi-
tion, and then install the bolt, screws
and quick fastener.
TIP
To install the quick fasteners, push the
center pin out so that it will protrude
from the fastener head, insert the fas-
tener into the cowling, and then push
the protruding pin in until it is flush with
the fastener head.
Cowling B
To remove the cowling
Remove the quick fastener, screws
and bolt, and then take the cowling off.
1. Cowling A
1. Cowling C
2. Cowling B
ZAUM16161
ZAUM161512
1. Screw
2. Bolt
3. Cowling A
4. Quick fastener
ZAUM161734
1
2
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Periodic maintenance and adjustment
6-8
6To install the cowling
Place the cowling in the original posi-
tion, and then install the bolt, screws
and quick fastener.
Cowling C
To remove the cowling
1. Remove the cowling B. (See page
6-7.)
2. Remove the quick fastener and
screws, and then take the cowling
off.To install the cowling
1. Place the cowling in the original
position, and then install the
screws and quick fastener.
2. Install the cowling B. (See page
6-7.)
1. Screw
2. Quick fastener
3. Cowling B
4. Bolt
1. Cowling C
2. Screw
3. Quick fastener
ZAUM1618
1
ZAUM1619
2
1
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Periodic maintenance and adjustment
6-9
6
EAU19623
Checking the spark plug
The spark plug is an important engine
component, which should be checked
periodically, preferably by a Yamaha
dealer. Since heat and deposits will
cause any spark plug to slowly erode,
it should be removed and checked in
accordance with the periodic mainte-
nance and lubrication chart. In addi-
tion, the condition of the spark plug
can reveal the condition of the engine.
The porcelain insulator around the
center electrode of the spark plug
should be a medium-to-light tan (the
ideal color when the vehicle is ridden
normally). If the spark plug shows a
distinctly different color, the engine
could be operating improperly. Do not
attempt to diagnose such problems
yourself. Instead, have a Yamaha deal-
er check the vehicle.
If the spark plug shows signs of elec-
trode erosion and excessive carbon or
other deposits, it should be replaced.
Before installing a spark plug, the
spark plug gap should be measured
with a wire thickness gauge and, if
necessary, adjusted to specification.Clean the surface of the spark plug
gasket and its mating surface, and
then wipe off any grime from the spark
plug threads.
TIP
If 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
specified torque as soon as possible.
Specified spark plug:
NGK/MR8E9
1. Spark plug gap
Spark plug gap:
0.8–0.9 mm (0.031–0.035 in)
Tightening torque:
Spark plug:
12.5 N·m (1.25 kgf·m, 9.22 lb·ft)
1
ZAUM0037
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Periodic maintenance and adjustment
6-10
6
EAUM4051
Engine oil and oil filter ele-
ment
The engine oil level should be checked
before each ride. In addition, the oil
must be changed and the oil filter ele-
ment replaced at the intervals specified
in the periodic maintenance and lubri-
cation chart.
To check the engine oil level
1. Place the vehicle on a level sur-
face and hold it in an upright posi-
tion. 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.
NOTICE: Do not operate the ve-
hicle until you know that the en-
gine oil level is sufficient.
[ECA10012]
TIP
The engine oil should be between the
minimum and maximum level marks.
4. If the engine oil is below the mini-
mum level mark, add sufficient oil
of the recommended type to raise
it to the correct level.
5. Install the oil filler cap.
To change the engine oil (with or
without oil filter element replace-
ment)
1. Remove cowling A. (See page
6-7.)
2. Start the engine, warm it up for
several minutes, and then turn it
off.
3. Place an oil pan under the engine
to collect the used oil.
4. Remove the engine oil filler cap
and the drain bolt along with the
O-ring, compression spring, and
engine oil strainer, to drain the oil
from the crankcase. NOTICE:
When removing the engine oil
drain bolt, the O-ring, compres-
sion spring, and oil strainer will
fall out. Take care not to lose
these parts.
[ECA11002]
1. Engine oil filler cap
ZAUM1610
1. Dipstick
2. Maximum level mark
3. Minimum level mark
1
2
3
ZAUE1300
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Periodic maintenance and adjustment
6-11
6 5. Clean the engine oil strainer with
solvent.
TIP
Skip to step 9 when only changing
the oil.
Perform steps 6–8 when replacing
the oil filter element.
6. Remove the oil filter element cover
by removing the bolts.
7. Remove and replace the oil filter
element and O-ring.8. Install the oil filter element cover
by installing the bolts, then tight-
ening them to the specified
torque.
TIP
Make sure that the O-ring is properly
seated.
9. Install the engine oil strainer, com-
pression spring, O-ring and the
engine oil drain bolt, and then
tighten it to the specified torque.
NOTICE: Before installing the
engine oil drain bolt, do not for-
get to install the O-ring, com-
pression spring, and oil strainer
in position.
[ECA10422]
10. Refill with the specified amount of
the recommended engine oil, and
then install and tighten the oil filler
cap.
1. Engine oil drain bolt
2. O-ring
3. Compression spring
4. Strainer
5. Oil pan
1. Bolt
2. Oil filter element cover
2 3 4
51
ZAUE0672
1. Oil filter element
2. O-ring
Tightening torques:
Oil filter element cover bolt:
10 N·m (1.0 kgf·m, 7.4 lb·ft)
Tightening torques:
Engine oil drain bolt:
32 N·m (3.2 kgf·m, 24 lb·ft)
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Periodic maintenance and adjustment
6-12
6
NOTICE
ECA11621
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.
11. Start the engine, and then let it idle
for several minutes while checking
it for oil leakage. If oil is leaking,
immediately turn the engine off
and check for the cause.
12. Turn the engine off, and then
check the oil level and correct it if
necessary.
EAU85450
Why Yamalube
YAMALUBE oil is a Genuine YAMAHA
Part born of the engineers’ passion
and belief that engine oil is an impor-
tant liquid engine component. We form
teams of specialists in the fields of me-
chanical engineering, chemistry, elec-
tronics and track testing, and have
them develop the engine together with
the oil it will use. Yamalube oils take full
advantage of the base oil’s qualities
and blend in the ideal balance of addi-
tives to make sure the final oil clears
our performance standards. Thus,
Yamalube mineral, semisynthetic and
synthetic oils have their own distinct
characters and value. Yamaha’s expe-
rience gained over many years of re-
search and development into oil since
the 1960’s helps make Yamalube the
best choice for your Yamaha engine.
Recommended engine oil:
See page 8-1.
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)
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Periodic maintenance and adjustment
6-13
6
EAU20071
Coolant
The coolant level should be checked
before each ride. In addition, the cool-
ant must be changed at the intervals
specified in the periodic maintenance
and lubrication chart.
EAUE3460To check the coolant level
1. Place the vehicle on a level sur-
face.
2. Remove cowling C of left side.
(See page 6-7.)
3. Hold the vehicle in an upright po-
sition.
TIP
The coolant level must be
checked on a cold engine since
the level varies with engine tem-
perature.
Make sure that the vehicle is posi-
tioned straight up when checking
the coolant level. A slight tilt to the
side can result in a false reading.
4. Check the coolant level in the
coolant reservoir.
TIP
The coolant should be between the
minimum and maximum level marks.
5. If the coolant is at or below the
minimum level mark, remove the
coolant reservoir cap.
6. Add coolant to the maximum level
mark, and then install the coolant
reservoir cap. WARNING! Re-
move only the coolant reservoir
cap. Never attempt to remove
the radiator cap when the en-
gine is hot.
[EWA15162] NOTICE: If
coolant is not available, use dis-
tilled water or soft tap water in-
stead. Do not use hard water or
salt water since it is harmful to
the engine. If water has been
used instead of coolant, replace
it with coolant as soon as possi-
ble, otherwise the cooling sys-
tem will not be protected
1. Coolant reservoir
2. Maximum level mark
3. Minimum level mark
1. Coolant reservoir cap
1
2
3FULL
LOW
ZAUE3384
1
ZAUE3385
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Periodic maintenance and adjustment
6-14
6against frost and corrosion. If
water has been added to the
coolant, have a Yamaha dealer
check the antifreeze content of
the coolant as soon as possible,
otherwise the effectiveness of
the coolant will be reduced.
[ECA10473]
7. Install the cowling.
EAU33032Changing the coolant
The coolant must be changed at the in-
tervals specified in the periodic mainte-
nance and lubrication chart. Have a
Yamaha dealer change the coolant.
WARNING! Never attempt to remove
the radiator cap when the engine is
hot.
[EWA10382]EAUM2391
Replacing the air filter ele-
ment and cleaning the check
hose
The air filter element should be re-
placed at the intervals specified in the
periodic maintenance and lubrication
chart. Have a Yamaha dealer replace
the air filter element more frequently if
you are riding in unusually wet or dusty
areas. In addition, the air filter check
hose must be frequently checked and
cleaned if necessary.
To clean the air filter check hose
1. Check the hose on the side of the
air filter case for accumulated dirt
or water.
2. If dirt or water is visible, remove
the hose, clean it, and then install
it.
Coolant reservoir capacity (up to
the maximum level mark):
0.15 L (0.16 US qt, 0.13 Imp.qt)
1. Air filter check hose
ZAUM1594
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Periodic maintenance and adjustment
6-15
6
EAU34302
Adjusting the engine idling
speed
The engine idling speed must be
checked and, if necessary, adjusted as
follows at the intervals specified in the
periodic maintenance and lubrication
chart.
The engine should be warm before
making this adjustment.
Check the engine idling speed and, if
necessary, adjust it to specification by
turning the idle adjusting screw. To in-
crease the engine idling speed, turn the
screw in direction (a). To decrease the
engine idling speed, turn the screw in
direction (b).
TIP
If the specified idling speed cannot be
obtained as described above, have a
Yamaha dealer make the adjustment.
EAU48434
Adjusting the throttle grip free
play
Measure the throttle grip free play as
shown.
Periodically check the throttle grip free
play and, if necessary, adjust it as fol-
lows.
TIP
The engine idling speed must be cor-
rectly adjusted before checking and
adjusting the throttle grip free play.
1. Slide the rubber cover back.
2. Loosen the locknut.
3. To increase the throttle grip free
play, turn the adjusting nut in di-
rection (a). To decrease the throt-
tle grip free play, turn the adjusting
nut in direction (b).1. Idle adjusting screw
Engine idling speed:
1250–1550 r/min
ZAUE3388
(a)(b)
1
1. Throttle grip free play
Throttle grip free play:
3.0–5.0 mm (0.12–0.20 in)
ZAUM1595
1
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Periodic maintenance and adjustment
6-16
64. Tighten the locknut and then slide
the rubber cover to its original po-
sition.
EAU21403
Valve clearance
The valves are an important engine
component, and since valve clearance
changes with use, they must be
checked and adjusted at the intervals
specified in the periodic maintenance
chart. Unadjusted valves can result in
improper air-fuel mixture, engine
noise, and eventually engine damage.
To prevent this from occurring, have
your Yamaha dealer check and adjust
the valve clearance at regular intervals.
TIP
This service must be performed when
the engine is cold.
1. Adjusting nut
2. Locknut
ZAUM159612(a)
(b)
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