2017 YAMAHA YS125 fuel cap

Table of contentsSafety information ............................ 1-1
Description ....................................... 2-1
Left view ......................................... 2-1
Right view ....................................... 2-2
Controls and instruments ............... 2-3
Instrument an d control functions ... 3-1
Main switch/steering lock............... 3-1
Indicator lights and warning light ............................................. 3-2
Multi-function meter unit ................ 3-3
Handlebar switches ........................ 3-5
Clutch lever .................................... 3-6
Shift pedal ...................................... 3-6
Brake lever...................................... 3-7
Brake pedal .................................... 3-7
Fuel tank cap .................................. 3-8
Fuel ................................................. 3-8
Catalytic converters ..................... 3-10
Seat .............................................. 3-11
Adjusting the shock absorber assemblies ................................ 3-11
Sidestand ..................................... 3-12
Ignition circuit cut-off system ....... 3-13 For your safety – pre-operation
checks
............................................... 4-1
Operation an d important ri din g
points ................................................. 5-1
Starting the engine .......................... 5-1
Shifting ............................................ 5-2
Tips for reducing fuel consumption ................................ 5-3
Engine break-in ............................... 5-3
Parking ............................................ 5-4
Perio dic maintenance an d
a d justment ........................................ 6-1
Owner’s tool kit ............................... 6-2
Periodic maintenance chart for the emission control system .............. 6-3
General maintenance and lubrication chart ........................... 6-4
Removing and installing the
cowling and panels ...................... 6-8
Checking the spark plug ............... 6-10
Engine oil and oil filter element ..... 6-11
Cleaning the air filter element and cleaning the check hose ............ 6-14
Adjusting the engine idling
speed ......................................... 6-16
Checking the throttle grip free play ............................................ 6-16
Valve clearance ............................. 6-17
Tires .............................................. 6-17 Cast wheels .................................. 6-19
Adjusting the clutch lever free
play ............................................ 6-19
Checking the brake lever free play ............................................ 6-20
Adjusting the brake pedal free play ............................................ 6-21
Brake light switches ..................... 6-21
Checking the front brake pads
and rear brake shoes ............... 6-22
Checking the brake fluid level ...... 6-22
Changing the brake fluid ............. 6-23
Drive chain slack........................... 6-24
Cleaning and lubricating the
drive chain ................................. 6-25
Checking and lubricating the cables ........................................ 6-26
Checking and lubricating the throttle grip and cable ............... 6-26
Checking and lubricating the
brake and shift pedals............... 6-26
Checking and lubricating the brake and clutch levers ............. 6-27
Checking and lubricating the centerstand and sidestand........ 6-28
Lubricating the swingarm
pivots......................................... 6-28
Checking the front fork ................. 6-29
Checking the steering................... 6-29
Checking the wheel bearings ....... 6-30
Battery .......................................... 6-30UBT4E0E0.book Page 1 Thursday, November 17, 2016 10:55 AM

Safety information
1-5
1operator and may limit control
ability, therefore, such accesso-
ries are not recommended.
 Use caution when adding electri-
cal accessories. If electrical ac-
cessories exceed the capacity of
the motorcycle’s electrical sys-
tem, an electric failure could re-
sult, which could cause a
dangerous loss of lights or engine
power.
Aftermarket Tires an d Rims
The tires and rims that came with your
motorcycle were designed to match
the performance capabilities and to
provide the best combination of han-
dling, braking, and comfort. Other
tires, rims, sizes, and combinations
may not be appropriate. Refer to page
6-17 for tire specifications and more in-
formation on replacing your tires.
Transportin g the Motorcycle
Be sure to observe following instruc-
tions before transporting the motorcy-
cle in another vehicle.  Remove all loose items from the
motorcycle. 
Check that the fuel cock (if
equipped) is in the “OFF” position
and that there are no fuel leaks.
 Point the front wheel straight
ahead on the trailer or in the truck
bed, and choke it in a rail to pre-
vent movement.
 Shift the transmission in gear (for
models with a manual transmis-
sion).
 Secure the motorcycle with tie-
downs or suitable straps that are
attached to solid parts of the mo-
torcycle, such as the frame or up-
per front fork triple clamp (and not,
for example, to rubber-mounted
handlebars or turn signals, or
parts that could break). Choose
the location for the straps carefully
so the straps will not rub against
painted surfaces during transport.
 The suspension should be com-
pressed somewhat by the tie-
downs, if possible, so that the mo-
torcycle will not bounce exces-
sively during transport.
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Description
2-1
2
EAU10411
Left view
4
7
1
2
8
9
3
6
5
10
1. Auxiliary light (page 6-34)
2. Headlight (page 6-33)
3. Fuel tank cap (page 3-8)
4. Idle adjusting screw (page 6-16)
5. Air filter element (page 6-14)
6. Seat (page 3-11)
7. Shock absorber assembly spring preload adjusting ring (page 3-11)
8. Brake/tail light (page 6-35) 9. License plate light (page 6-36)
10.Shift pedal (page 3-6)
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Instrument and control functions
3-8
3
EAU13003
Fuel tank capTo remove the fuel tank cap
Insert the key into the lock and turn it
1/4 turn clockwise. The lock will be re-
leased and the fuel tank cap can be re-
moved.
To install the fuel tank cap
1. Push the fuel tank cap into posi- tion with the key inserted in the
lock.
2. Turn the key counterclockwise to the original position, and then re-
move it.
TIPThe fuel tank cap cannot be installed
unless the key is in the lock. In addi-
tion, the key cannot be removed if the
cap is not properly installed and
locked.
WARNING
EWA11142
Make sure that the fuel tank cap is
properly installe d before ri din g.
Leakin g fuel is a fire hazar d.
EAU13213
FuelMake sure there is sufficient gasoline in
the tank.
WARNING
EWA10882
Gasoline an d gasoline vapors are
extremely flammab le. To avoid fires
an d explosions an d to re duce the
risk of injury when refuelin g, follow
these instructions.1. Before refueling, turn off the en- gine and be sure that no one is sit-
ting on the vehicle. Never refuel
while smoking, or while in the vi-
cinity of sparks, open flames, or
other sources of ignition such as
the pilot lights of water heaters
and clothes dryers.
2. Do not overfill the fuel tank. Stop filling when the fuel reaches the
bottom of the filler tube. Because
fuel expands when it heats up,
heat from the engine or the sun
can cause fuel to spill out of the
fuel tank.
1. Unlock.
1
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Instrument and control functions
3-9
3
3. Wipe up any spilled fuel immedi-ately. NOTICE: Immediately
wipe off spille d fuel with a clean,
d ry, soft cloth, since fuel may
d eteriorate painted surfaces or
plastic parts.
[ECA10072]
4. Be sure to securely close the fuel tank cap.
WARNING
EWA15152
Gasoline is poisonous an d can cau-
se injury or death. Han dle gasoline
with care. Never siphon gasoline by
mouth. If you shoul d swallow some
g asoline or inhale a lot of g asoline
vapor, or g et some gasoline in your
eyes, see your d octor immediately. If g
asoline spills on your skin, wash
with soap an d water. If g asoline
spills on your clothin g, chan ge your
clothes.
EAU76860
NOTICE
ECA11401
Use only unlea ded g asoline. The use
of lea ded g asoline will cause severe
d amag e to internal en gine parts,
such as the valves an d piston rin gs,
as well as to the exhaust system.
TIP This mark identifies the recom-
mended fuel for this vehicle as
specified by European regulation
(EN228).
 Check that gasoline nozzle has
the same identifier when fueling.Your Yamaha engine has been de-
signed to use regular unleaded gaso-
line with a research octane number of
95 or higher. If knocking (or pinging)
occurs, use a gasoline of a different
brand or premium unleaded fuel. Use
of unleaded fuel will extend spark plug
life and reduce maintenance costs.
1. Fuel tank filler tube
2. Maximum fuel level
1
2
Recommen ded fuel:
Regular unleaded gasoline (Gasohol
[E10] acceptable)
Fuel tank capacity:
14 L (3.7 US gal, 3.1 Imp.gal)
Fuel reserve amount: 2.2 L (0.58 US gal, 0.48 Imp.gal)
E10
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Motorcycle care and stora ge
7-4
7 2. Fill up the fuel tank and add fuel
stabilizer (if available) to prevent
the fuel tank from rusting and the
fuel from deteriorating.
3. Perform the following steps to protect 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.)
WARNING! To prevent d am-
a g e or injury from sparkin g,
make sure to groun d the
spark plu g electro des while
turnin g the en gine over.
[EWA10952]
e. Remove the spark plug cap
from the spark plug, and then
install the spark plug and the
spark plug cap.
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 char- ge it. Store it in a cool, dry place
and charge it once a month. Do
not store the battery in an exces-
sively 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
6-30.
TIPMake any necessary repairs before
storing the motorcycle.
UBT4E0E0.book Page 4 Thursday, November 17, 2016 10:55 AM

Specifications
8-1
8
Dimensions:Overall length:2005 mm (78.9 in)
Overall width:
735 mm (28.9 in)
Overall height: 1050 mm (41.3 in)
Seat height: 795 mm (31.3 in)
Wheelbase:
1320 mm (52.0 in)
Ground clearance: 150 mm (5.91 in)
Minimum turning radius: 2.2 m (7.22 ft)Wei ght:Curb weight:
129 kg (284 lb)Engine:Combustion cycle:
4-stroke
Cooling system: Air cooled
Valve train: SOHC
Number of cylinders:
Single cylinder
Displacement: 125 cm³
Bore × stroke:
52.4 × 57.9 mm (2.06 × 2.28 in)
Compression ratio:
10.0 : 1 Starting system:
Electric starter
Lubrication system: Wet sump
Engine oil:Recommended brand:
YAMALUBE
SAE viscosity grades: 10W-40, 20W-40
Recommended engine oil grade: API service SG type or higher, JASO
standard MA
Engine 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)Air filter:Air filter element:Dry element
Fuel:Recommended fuel:Regular unleaded gasoline (Gasohol [E10]
acceptable)
Fuel tank capacity: 14 L (3.7 US gal, 3.1 Imp.gal)
Fuel reserve amount:
2.2 L (0.58 US gal, 0.48 Imp.gal)Fuel injection:Throttle body:ID mark:BT41 00Spark plu g(s):Manufacturer/model:
NGK/CPR8EA-9
Spark plug gap: 0.8–0.9 mm (0.031–0.035 in)Clutch:Clutch type:
Wet, multiple-discDrivetrain:Primary reduction ratio:3.409 (75/22)
Final drive:
Chain
Secondary reduction ratio: 3.071 (43/14)
Transmission type: Constant mesh 5-speed
Gear ratio:
1st:2.714 (38/14)
2nd:
1.789 (34/19)
010305070 90110
130 ˚F
-20 -10 0 10 20 3040
50 ˚C
SAE 10W-40
SAE 20W-40
UBT4E0E0.book Page 1 Thursday, November 17, 2016 10:55 AM

10-1
10
IndexAAir filter element and check hose,
cleaning .............................................. 6-14
Auxiliary light bulb, replacing ................ 6-34BBattery .................................................. 6-30
Brake and clutch levers, checking and lubricating ........................................... 6-27
Brake and shift pedals, checking and
lubricating ........................................... 6-26
Brake fluid, changing ............................ 6-23
Brake fluid level, checking .................... 6-22
Brake lever .............................................. 3-7
Brake lever free play, checking............. 6-20
Brake light switches.............................. 6-21
Brake pads and shoes, checking ......... 6-22
Brake pedal............................................. 3-7
Brake pedal free play, adjusting ........... 6-21
Brake/tail light bulb, replacing .............. 6-35CCables, checking and lubricating ......... 6-26
Care ........................................................ 7-1
Catalytic converters .............................. 3-10
Centerstand and sidestand, checking and lubricating .................................... 6-28
Clutch lever ............................................. 3-6
Clutch lever free play, adjusting ........... 6-19
Cowling and panels, removing and installing................................................ 6-8DData recording, vehicle ........................... 9-2
Diagnostic connector.............................. 9-2
Dimmer switch ........................................ 3-5
Drive chain, cleaning and lubricating .... 6-25 Drive chain slack .................................. 6-24
EEco indicator light................................... 3-2
Engine break-in ...................................... 5-3
Engine idling speed .............................. 6-16
Engine oil and oil filter element ............ 6-11
Engine serial number .............................. 9-1
Engine trouble warning light ................... 3-2FFront fork, checking ............................. 6-29
Fuel ......................................................... 3-8
Fuel consumption, tips for reducing ...... 5-3
Fuel tank cap .......................................... 3-8
Fuse, replacing ..................................... 6-31HHandlebar switches ................................ 3-5
Headlight bulb, replacing ..................... 6-33
High beam indicator light ....................... 3-2
Horn switch ............................................ 3-5IIdentification numbers ............................ 9-1
Ignition circuit cut-off system ............... 3-13
Indicator lights and warning light ........... 3-2LLicense plate light bulb, replacing........ 6-36MMain switch/steering lock....................... 3-1
Maintenance and lubrication, periodic ... 6-4
Maintenance, emission control
system.................................................. 6-3
Matte color, caution ............................... 7-1
Model label ............................................. 9-1
Multi-function meter unit ........................ 3-3
NNeutral indicator light ..............................3-2PParking ....................................................5-4
Part locations ..........................................2-1
Pass switch .............................................3-5SSafety information ...................................1-1
Seat .......................................................3-11
Shifting ....................................................5-2
Shift pedal ...............................................3-6
Shock absorber assemblies, adjusting .............................................3-11
Sidestand ..............................................3-12
Spark plug, checking ............................6-10
Specifications .........................................8-1
Starting the engine ..................................5-1
Start switch .............................................3-6
Steering, checking ................................6-29
Storage ...................................................7-3
Swingarm pivots, lubricating ................6-28TThrottle grip and cable, checking and lubricating ...........................................6-26
Throttle grip free play, checking ...........6-16
Tires ......................................................6-17
Tool kit ....................................................6-2
Troubleshooting ....................................6-39
Troubleshooting chart ...........................6-41
Turn signal indicator light........................3-2
Turn signal light bulb, replacing ............6-35
Turn signal switch ...................................3-5VValve clearance .....................................6-17
UBT4E0E0.book Page 1 Thursday, November 17, 2016 10:55 AM