engine YAMAHA YS125 2017 Owner's Manual

Periodic maintenance an d a djustment
6-3
6
EAU71020
TIP The annual checks must b e performed every year, except if a kilometer- based maintenance, or for the UK, a
milea ge- base d maintenance, is performe d instead .
 From 30000 km (17500 mi), repeat the maintenance intervals starting from 6000 km (3500 mi).
 Items marked with an asterisk should be performed by a Yamaha dealer as they require special tools, data and tech-
nical skills.
EAU71040
Perio dic maintenance chart for the emission control systemNO. ITEM CHECK OR MAINTENANCE JOB ODOMETER READING
ANNUAL
CHECK
1000 km
(600 mi) 6000 km
(3500 mi) 12000 km
(7000 mi) 18000 km
(10500 mi) 24000 km
(14000 mi)
1 *Fuel line • Check fuel hoses for cracks or
damage.
• Replace if necessary. √√√√√
2 *Spark plu g • Check condition.
• Adjust gap and clean.
√√
• Replace. √√
3 *Valve clearance • Check and adjust. √√√√
4 *Fuel injection • Check and adjust engine idle
speed. √√√√√√
5 *Exhaust system • Check for leakage.
• Tighten if necessary.
• Replace gasket if necessary. √√√√√
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Periodic maintenance an d a djustment
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6
19 Shift pe
dal pivot
shaft • Lubricate with lithium-soap-
based grease. √√√√√
20 *Unifie
d b rake sys-
tem • Check cable free play, and adjust
if necessary. √√√√√√
• Lubricate link pivot of brake pedal with lithium-soap-based grease. √√√√√
21 Si
destan d, center-
stan d • Check operation.
• Lubricate with lithium-soap-
based grease. √√√√√
22 *Sidestan d switch • Check operation and replace if
necessary. √√√√√√
23 *Front fork • Check operation and for oil leak-
age.
• Replace if necessary. √√√√
24 *Shock a
bsor ber as-
sem blies • Check operation and for oil leak-
age.
• Replace if necessary. √√√√
25 En gine oil • Change (warm engine before
draining).
• Check oil level and vehicle for oil leakage. √√√√√√
26 En
gine oil filter ele-
ment •Replace.
√√√
27 *Front an
d rear
b rake switches • Check operation.
√√√√√√
28 *Movin
g parts an d
ca bles • Lubricate.
√√√√√
NO. ITEM CHECK OR MAINTENANCE JOB
OD OMETER READING
ANNUAL
CHECK
1000 km
(600 mi) 6000 km
(3500 mi) 12000 km
(7000 mi) 18000 km
(10500 mi) 24000 km
(14000 mi)
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Periodic maintenance an d a djustment
6-10
6
EAU78710
Checkin g the spark plugThe 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 main-
tenance and lubrication chart. In addi-
tion, the condition of the spark plug
can reveal the condition of the engine.
To remove the spark plu g
1. Remove cowling A. (See page 6-8.)
2. Remove the Y.R.C.S. (Yamaha Ram-Air Cooling System) cap by
removing the bolts and then, re-
move the spark plug cap. 3. Remove the spark plug as shown,
with the spark plug wrench includ-
ed in the owner’s tool kit. To check the spark plu
g
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 vehi-
cle 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 electrodeerosion 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 specifi-
cation.
1. Cowling A
2. Y.R.C.S (Yamaha Ram–Air Cooling System) cap
3. Bolt
4. Spark plug cap
1. Spark plug wrench
4 32
1
1
Specified
spark plu g:
NGK/CPR8EA-9
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Periodic maintenance an d a djustment
6-11
6
To install the spark plu g
1. Clean the surface of the spark plug gasket and its mating surfa-
ce, 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
specified torque as soon as possible.3. Install the spark plug cap.
4. Install the Y.R.C.S. (Yamaha Ram-Air Cooling System) cap by install-
ing the bolts.
5. Install the cowling.
EAU78803
En gine oil an d oil filter ele-
mentThe 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 en gine 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 engine oil filler
cap, wipe the dipstick clean, insert
it back into the oil filler hole (with-
out screwing it in), and then re-
move it again to check the oil level.
WARNING! Never remove the
engine oil filler cap after hi gh-
speed operation, otherwise hot
en gine oil coul d spout out an d
cause damag e or injury. Always
let the en gine oil cool down suf-
1. Spark plug gapSpark plu g g ap:
0.8–0.9 mm (0.031–0.035 in)
Ti ghtenin g torque:
Spark plug: 13 N·m (1.3 kgf·m, 9.4 lb·ft)
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Periodic maintenance an d a djustment
6-12
6
ficiently
before removin g the oil
filler cap.
[EWA17640]
NOTICE: Do not
operate the vehicle until you
know that the en gine oil level is
sufficient.
[ECA10012]
TIPThe 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. Check the O-ring for damage, and replace it if necessary.
6. Install and tighten the engine oil filler cap.
To chan ge the en gine oil (with or
without oil filter element replace-
ment) 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.
TIPSkip steps 4–6 if the oil filter element is
not being replaced.4. Remove the oil filter element coverby removing the bolts.
1. Engine oil filler cap
1. O-ring
2. Engine oil dipstick
3. Maximum level mark
4. Minimum level mark
1
4 321
1. Engine oil drain bolt
2. Gasket
1. Bolt
2. Oil filter element cover
12
1
2
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Periodic maintenance an d a djustment
6-13
6 5. Remove and replace the oil filter
element and O-ring.
6. Install the oil filter element cover by installing the bolts, then tight-
ening them to the specified
torque.
TIPMake sure that the O-ring is properly
seated.7. Install the engine oil drain bolt andits new gasket, and then tighten
the bolt to the specified torque. 8. Refill with the specified amount of
the recommended engine oil.
NOTICE
ECA11621
In or der to prevent clutch slip-
pa ge (since the en gine oil also
lu bricates the clutch), do not
mix any chemical additives. Do
not use oils with a diesel speci-
fication of “CD” or oils of a hi gh-
er quality than specifie d. In
a ddition, do not use oils la beled
“ENERGY CONSERVING II” or
hi gher.
 Make sure that no forei gn mate-
rial enters the crankcase.
9. Check the O-ring for damage, and replace it if necessary.
10. Install and tighten the engine oil filler cap.NOTICE
ECA10441
After chan gin g the en gine oil, b e
sure to check the oil pressure as de-
scri bed b elow.To check the oil pressure
1. Remove cowling A. (See page 6-8.)
2. Remove the Y.R.C.S. (Yamaha Ram-Air Cooling System) cap.
(See page 6-10.)
1. Oil filter element
2. O-ringTightenin g torque:
Oil filter element cover bolt: 10 N·m (1.0 kgf·m, 7.2 lb·ft)
2 1
Ti
ghtenin g torque:
Engine oil drain bolt:
20 N·m (2.0 kgf·m, 14 lb·ft)
Recommen ded en gine oil:
See page 8-1.
Oil quantity:
Oil change:1.00 L (1.06 US qt, 0.88 Imp.qt)
With oil filter removal:
1.10 L (1.16 US qt, 0.97 Imp.qt)
1. Engine oil filler cap
2. O-ring
21
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Periodic maintenance an d a djustment
6-14
6
3. Loosen the bleed bolt, start the
engine and keep it idling until oil
flows out. If no oil comes out after
several minutes, turn the engine
off immediately and consult a
Yamaha dealer for inspection.
4. After checking the oil pressure, tighten the bleed bolt with the
specified torque.
5. Install the Y.R.C.S. (Yamaha Ram- Air Cooling System) cap.
6. Install the cowling. 7. 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.
8. Turn the engine off, check the oil level and correct it if necessary.
EAUW3321
Cleanin g the air filter element
an d cleanin g the check hoseThe air filter element should be cleaned
at the intervals specified in the periodic
maintenance and lubrication chart.
Clean the air filter element more fre-
quently 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 element
1. Remove panel A. (See page 6-8.)
2. Remove the air filter case cover by removing the screws, and then
pull the air filter element out.
1. Bleed boltTightenin g torque:
Bleed bolt: 7 N·m (0.7 kgf·m, 5.1 lb·ft)
1
1. Air filter case cover
2. Screw
2 2
1
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Periodic maintenance an d a djustment
6-16
6
EAU34302
A djustin g the en gine i dlin g
spee dThe 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).
TIPIf the specified idling speed cannot be
obtained as described above, have a
Yamaha dealer make the adjustment.
EAU21386
Checkin g the throttle grip free
playMeasure the throttle grip free play as
shown.
Periodically check the throttle grip free
play and, if necessary, have a Yamaha
dealer adjust it.
1. Idle adjusting screw
1
(b)
(a)
En gine i dlin g spee d:
1300–1500 r/min
1. Throttle grip free play
Throttle grip free play:
3.0–7.0 mm (0.12–0.28 in)
1
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Periodic maintenance and adjustment
6-17
6
EAU21402
Valve clearanceThe 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.
EAU69760
TiresTires are the only contact between the
vehicle and the road. Safety in all con-
ditions of riding depends on a relatively
small area of road contact. Therefore, it
is essential to maintain the tires in good
condition at all times and replace them
at the appropriate time with the speci-
fied tires.
Tire air pressure
The tire air pressure should be
checked and, if necessary, adjusted
before each ride.
WARNING
EWA10504
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
adjusted in accordance with the
riding speed and with the total weight of rider, passenger, car-
go, and accessories approved
for this model.
WARNING
EWA10512
Never overload your vehicle. Opera-
tion of an overloaded vehicle could
cause an accident.Tire air pressure (measured on cold
tires):
1 person:Front:
175 kPa (1.75 kgf/cm², 25 psi)
Rear: 200 kPa (2.00 kgf/cm², 29 psi)
2 persons: Front:175 kPa (1.75 kgf/cm², 25 psi)
Rear: 225 kPa (2.25 kgf/cm², 33 psi)
Maximum load:
Front:175 kPa (1.75 kgf/cm², 25 psi)
Rear:
250 kPa (2.50 kgf/cm², 36 psi)
Maximum load*: 171 kg (377 lb)
* Total weight of rider, passenger, car- go and accessories
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Periodic maintenance an d a djustment
6-41
6
EAUT1985
Trou bleshootin g chart
Check the fuel level in
the fuel tank.1. Fuel
There is enough fuel.
There is no fuel.
Check the battery.
Supply fuel.
The engine does not start.
Check the battery.
Operate the electric starter.4. Compression
There is compression.
There is no compression.
The engine does not start.
Have a Yamaha dealer check the vehicle.Have a Yamaha dealer check the vehicle.
Remove the spark plug
and check the electrodes.3. Ignition
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 compression.
Operate the electric starter.2. Battery
The engine turns over
quickly.
The engine turns over
slowly.
The battery is good.
DryWet
Operate the electric starter.
Check the battery lead connections,
and have a Yamaha dealer charge
the battery if necessary.
The engine does not start.
Check the ignition.
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