2011 YAMAHA CYGNUS 125 engine

1
2
3
4
5
6
7
8
9
6-12
EAU1722A
PERIODIC MAINTENANCE AND ADJUSTMENT
EAU20065
Final transmission oilThe fi nal transmission case must be
checked for oil leakage before each
ride. If any leakage is found, have a
Yamaha dealer check and repair the
scooter. In addition, the fi nal transmis-
sion oil must be changed as follows at
the intervals specifi ed in the periodic
maintenance and lubrication chart.
1. Start the engine, warm up the fi -
nal transmission oil by riding the
scooter for several minutes, and
then stop the engine.
2. Place the scooter on the center-
stand.
3. Place an oil pan under the fi nal
transmission case to collect the
used oil.
ZAUM00**
1
1. Final transmission oil fi ller cap4. Remove the fi nal transmission oil
fi ller cap and its O-ring from the
fi nal transmission case.
5. Remove the fi nal transmission oil
drain bolt and its gasket to drain
the oil from the fi nal transmission
case.
ZAUM00**
1
1. Final transmission oil drain bolt6. Install the fi nal transmission oil
drain bolt and its new gasket, and
then tighten the bolt to the speci-
fi ed torque.Tightening torque:
Final transmission oil drain bolt:
23 Nm (2.3 m·kgf, 16.6 ft·lbf)7. Refi ll with the specifi ed amount of
the recommended fi nal transmis-
sion oil. WARNING! Make sure
that no foreign material enters
the nal transmission case.
Make sure that no oil gets on
the tire or wheel.
[EWA11311]
2('KPFF
J`.,*f J`.,Q/f2J`.,`oJ`.,I\6"

1
2
3
4
5
6
7
8
9
6-13
EAU1722A
PERIODIC MAINTENANCE AND ADJUSTMENTRecommended nal transmission
oil:
See page 8-1.
Oil quantity:
0.11 L (0.12 US qt, 0.10 Imp.qt)8. Install the fi nal transmission oil
fi ller cap and its new O-ring, and
then tighten the oil fi ller cap.
9. Check the fi nal transmission case
for oil leakage. If oil is leaking,
check for the cause.
EAUT3120
Air lter and V-belt case air
lter elementsThe air fi lter and V-belt case air fi lter
elements should be cleaned at the in-
tervals specifi ed in the periodic main-
tenance and lubrication chart. Check
both fi lter elements more frequently
if you are riding in unusually wet or
dusty areas. The air fi lter check hoses
must be frequently checked and
cleaned if necessary.
Replacing the air lter element
1. Place the scooter on the center-
stand.2. Remove the air fi lter case cover
by removing the screws.
ZAUM00**
1
2(✕6)
1. Air fi lter case cover
2. Screw3. Pull the air fi lter element out.
4. Insert a new air fi lter element into
the air fi lter case.
NOTICE:
Make
sure that the air lter element
is properly seated in the air
lter case. The engine should
never be operated without
the air lter element installed,
otherwise the piston(s) and/or
cylinder(s) may become exces-
sively worn.
[ECA10481]
5. Install the air fi lter case cover by
installing the screws.
2('KPFF
J`.,*f J`.,Q/f2J`.,`oJ`.,I\6"

1
2
3
4
5
6
7
8
9
6-15
EAU1722A
PERIODIC MAINTENANCE AND ADJUSTMENTTIPThe air fi lter element should be wet
but not dripping.Recommended oil:
Yamaha foam air fi lter oil or other
quality foam air fi lter oil5. Insert the element into the air fi l-
ter case.
6. Install the fi lter element holder by
installing the screw.
7. Install the V-belt air fi lter case
cover by installing the screws.
EAU21401
Valve clearanceThe valve clearance changes with
use, resulting in improper air-fuel mix-
ture and/or engine noise. To prevent
this from occurring, the valve clear-
ance must be adjusted by a Yamaha
dealer at the intervals specifi ed in the
periodic maintenance and lubrication
chart.
EAU21384
Checking the throttle grip
free playThe throttle grip free play should mea-
sure 3 ~ 5 mm (0.12 ~ 0.20 in) at the
inner edge of the throttle grip. Periodi-
cally check the throttle grip free play
and, if necessary, have a Yamaha
dealer adjust it.ZAUM00**
1
1. Throttle cable free play
2('KPFF
J`.,*f J`.,Q/f2J`.,`oJ`.,I\6"

1
2
3
4
5
6
7
8
9
6-21
EAU1722A
PERIODIC MAINTENANCE AND ADJUSTMENT
EAU43641
Lubricating the front and rear
brake leversZAUM00**ZAUM00**
The pivoting points of the front and
rear brake levers must be lubricated
at the intervals specifi ed in the period-
ic maintenance and lubrication chart.
EAU23095
Checking and lubricating the
cablesThe operation of all control cables
and the condition of the cables should
be checked before each ride, and
the cables and cable ends should be
lubricated if necessary. If a cable is
damaged or does not move smoothly,
have a Yamaha dealer check or re-
place it.
WARNING! Damage to the outer
housing of cables may result in
internal rusting and cause inter-
ference with cable movement.
Replace damaged cables as soon
as possible to prevent unsafe
conditions.
[EWA10711]
Recommended lubricant:
Yamaha Chain and Cable Lube or
engine oil
EAU23114
Checking and lubricating the
throttle grip and cableThe operation of the throttle grip
should be checked before each ride.
In addition, the cable should be lubri-
cated by a Yamaha dealer at the inter-
vals specifi ed in the periodic mainte-
nance chart.
The throttle cable is equipped with a
rubber cover. Make sure that the cov-
er is securely installed. Even though
the cover is installed correctly, it does
not completely protect the cable from
water entry. Therefore, use care not to
pour water directly onto the cover or
cable when washing the vehicle. If the
cable or cover becomes dirty, wipe
clean with a moist cloth.
2('KPFF
J`.,*f J`.,Q/f2J`.,`oJ`.,I\6"

1
2
3
4
5
6
7
8
9
6-31
EAU1722A
PERIODIC MAINTENANCE AND ADJUSTMENT
EAUT1981
Troubleshooting chart
Check the fuel level in
the fuel tank.1. Fuel
There is enough fuel.
There is no fuel.
Check the compression.
Supply fuel.
The engine does not start.
Check the compression.
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
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.
Have a Yamaha dealer
check the vehicle.
The engine does not start.
Check the battery.
Operate the electric starter.4. Battery
The engine turns over
quickly.
The engine turns over
slowly.
The battery is good.Check the battery lead connections,
and charge the battery if necessary.
DryWet
Operate the electric starter.
2('KPFF
J`.,*f J`.,Q/f2J`.,`oJ`.,I\6"

1
2
3
4
5
6
7
8
9
7-1
EAU25991
SCOOTER CARE AND STORAGE
EAU25991
SCOOTER CARE AND STORAGE
EAU37833
Matte color caution
ECA15192
NOTICESome models are equipped with
matte colored nished 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 nished parts.
EAU26094
CareWhile the open design of a scooter
reveals the attractiveness of the tech-
nology, it also makes it more vulner-
able. Rust and corrosion can develop
even if high-quality components are
used. A rusty exhaust pipe may go
unnoticed on a car, however, it de-
tracts from the overall appearance of
a scooter. Frequent and proper care
does not only comply with the terms of
the warranty, but it will also keep your
scooter looking good, extend its life
and optimize its performance.
Before cleaning
1. Cover the muffl er outlet with a
plastic bag after the engine has
cooled down.
2. Make sure that all caps and cov-
ers as well as all electrical cou-
plers and connectors, including
the spark plug cap, are tightly
installed.
3. Remove extremely stubborn dirt,
like oil burnt onto the crankcase,
with a degreasing agent and
a brush, but never apply such
products onto seals, gaskets and
wheel axles. Always rinse the dirt
and degreaser off with water.
Cleaning
ECA10783
NOTICE● 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 affected area
any longer than instructed.
Also, thoroughly rinse the area
off with water, immediately dry
it, and then apply a corrosion
protection spray.● Improper cleaning can dam-
age plastic parts (such as
cowlings, panels, windshields,
headlight lenses, meter lenses,
etc.) and the muf ers. Use only
a soft, clean cloth or sponge
with water to clean plastic.
However, if the plastic parts
cannot be thoroughly cleaned
2('KPFF
J`.,*f J`.,Q/f2J`.,`oJ`.,I\6"

1
2
3
4
5
6
7
8
9
7-4
EAU25991
SCOOTER CARE AND STORAGE
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.)
e. Remove the spark plug cap
from the spark plug, and then
install the spark plug and the
spark plug cap. WARNING!
To prevent damage or injury
from sparking, make sure to
ground the spark plug elec-
trodes while turning the en-gine over.
[EWA10951]
4. Lubricate all control cables and
the pivoting points of all levers
and pedals as well as of the
sidestand/centerstand.
5. Check and, if necessary, correct
the tire air pressure, and then
lift the scooter so that both of its
wheels are off the ground. Alter-
natively, turn the wheels a little
every month in order to prevent
the tires from becoming degraded
in one spot.
6. Cover the muffl er 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 excessively 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 6-24.
EAU36563
StorageShort-term
Always store your scooter in a cool,
dry place and, if necessary, protect
it against dust with a porous cover.
Be sure the engine and the exhaust
system are cool before covering the
scooter.
ECA10820
NOTICE● Storing the scooter in a poorly
ventilated room or covering it
with a tarp, while it is still wet,
will allow water and humidity to
seep in and cause rust.● To prevent corrosion, avoid
damp cellars, stables (because
of the presence of ammonia)
and areas where strong chemi-
cals are stored.
Long-term
Before storing your scooter for several
months:
1. Follow all the instructions in the
“Care” section of this chapter.
2('KPFF
J`.,*f J`.,Q/f2J`.,`oJ`.,I\6"

1
2
3
4
5
6
7
8
9
8-1
SPECIFICATIONS SPECIFICATIONS
EAU50910
DimensionsOverall length
1855 mm (73.0 in)
Overall width
685 mm (27.0 in)
Overall height
1130 mm (44.5 in)
Seat height
785 mm (30.9 in)
Wheelbase
1295 mm (51.0 in)
Ground clearance
113 mm (4.45 in)
Minimum turning radius
1900 mm (74.8 in)WeightCurb weight
120 kg (265 lb)EngineEngine type
Air cooled 4-stroke, SOHC
Cylinder arrangement
Single cylinder
Displacement
125 cm
3
Bore x stroke
52.4 x 57.9 mm (2.06 x 2.28 in)
Compression ratio
10.00 :1
Starting system
Electric starter and kickstarter
Lubrication system
Wet sump
Engine oilRecommended brand
YAMALUBE
Type
SAE 10W-30, 10W-40, 10W-50, 15W-40,
20W-40 or 20W-50
–20 –10 0
1020 30 40 50 ˚C 10 30 50 70 90 110 0 130 ˚F
SAE 10W-30
SAE 15W-40SAE 20W-40SAE 20W-50
SAE 10W-40SAE 10W-50
Recommended engine oil grade
API service SG type or higher, JASO
standard MAEngine oil quantityPeriodic oil change
0.90 L (0.95 US qt, 0.79 Imp.qt)Final transmission oilType
SAE 10W-30 type SE motor oil
Quantity
0.11 L (0.12 US qt, 0.10 Imp.qt)Air lterAir fi lter element
Wet elementFuelRecommended fuel
Regular unleaded gasoline onlyFuel tank capacity
7.4 L (1.96 US gal, 1.63 Imp.gal)
Throttle bodyID mark
4P91 00
Manufacturer
MIKUNISpark plug(s)Manufacturer/model
NGK/CR7E
Spark plug gap
0.7-0.8 mm (0.028-0.031 in)ClutchClutch type
Dry, centrifugal automaticTransmissionPrimary reduction ratio
1.000
Secondary reduction ratio
9.744 (38/13 40/12)
Final drive
Gear
Transmission type
V-belt automaticChassisFrame type
Backbone
Caster angle
27.00 degree
Trail
90 mm (3.5 in)Front tireType
Tubeless
2('KPFF
J`.,*f J`.,Q/f2J`.,`oJ`.,I\6"