YAMAHA CYGNUS 125 2007 Repair Manual

PERIODIC MAINTENANCE AND MINOR REPAIR
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9 fected. Thoroughly clean off any dirt
and fingerprints on the headlight
bulb using a cloth moistened with al-

cohol or thinner.
6. Install the headlight bulb cover,
and then connect the coupler.
7. Install the panel.
8. Have a Yamaha dealer adjust the
headlight beam if necessary.
EAUT1891
Replacing a front turn signal
light bulb
CAUTION:

ECA10670
It is advisable to have a Yamaha
dealer perform this job.
1. Place the scooter on the center-
stand.
2. Remove panel A. (See page 6-6.)
3. Remove the socket (together with
the bulb) by turning it counter-
clockwise.
4. Remove the defective bulb by
pushing it in and turning it counter-
clockwise.5. Insert a new bulb into the socket,
push it in, and then turn it clock-
wise until it stops.
6. Install the socket (together with the
bulb) by turning it clockwise.
7. Install the panel.
1. Turn signal light bulb
2. Socket
ZAUM00**
1
2

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EAUT1922
Replacing the tail/brake light
bulb or a rear turn signal light
bulb
Tail/brake light bulb
1. Remove the tail/brake light lens by
removing the screws.
2. Remove the defective bulb by
pushing it in and turning it counter-
clockwise.
3. Insert a new bulb into the socket,
push it in, and then turn it clock-
wise until it stops.
4. Install the lens by installing thescrews.
Rear turn signal light bulb
1. Remove the tail/brake light lens by
removing the screws.
2. Remove the turn signal light lens
by removing the screws.
3. Remove the defective bulb by
pushing it in and turning it counter-
clockwise.
4. Insert a new bulb into the socket,
push it in, and then turn it clock-
wise until it stops.
5. Install the turn signal light lens by
installing the screws.
6. Install the tail/brake light lens by in-
stalling the screws.
CAUTION:

ECA10680
Do not overtighten the screws, oth-
erwise the lens may break.
EAUT1962
Replacing an auxiliary light
bulb
This model is equipped with two auxil-
iary lights. If an auxiliary light bulb burns
out, replace it as follows.
1. Remove panel B. (See page 6-6.)
2. Remove the auxiliary light socket
(together with the bulb) by turning
it counterclockwise.
3. Remove the defective bulb by pull-
ing it out.
4. Insert a new bulb into the socket.
5. Install the auxiliary light socket (to-
gether with the bulb) by turning it
clockwise.
1. Tail/brake light lens
2. Turn signal light lens
3. Rear turn signal light bulb
4. Tail/brake light bulb
ZAUM00**3
1
2
4

1. Auxiliary light bulb
2. Socket
ZAUM00**
12

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6. Install the panel.

EAU25860
Troubleshooting
Although Yamaha scooters receive a
thorough inspection before shipment
from the factory, trouble may occur dur-
ing operation. Any problem in the fuel,
compression, or ignition systems, for
example, can cause poor starting and
loss of power.
The following troubleshooting chart
represents a quick and easy procedure
for checking these vital systems your-
self. However, should your scooter re-
quire any repair, take it to a Yamaha
dealer, whose skilled technicians have
the necessary tools, experience, and
know-how to service the scooter prop-
erly.
Use only genuine Yamaha replace-
ment parts. Imitation parts may look like
Yamaha parts, but they are often inferi-
or, have a shorter service life and can
lead to expensive repair bills.

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EAUT1980
Troubleshooting chart
WARNING

EWA10840
Keep away open flames and do not smoke while checking or working on the fuel system.
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.

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9

SCOOTER CARE AND STORAGE
EAU37833
Matte color caution
CAUTION:

ECA15192
Some models are equipped with
matte colored finished 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 fin-
ished parts.
EAU26090
Care
While the open design of a scooter re-
veals the attractiveness of the technol-
ogy, it also makes it more vulnerable.
Rust and corrosion can develop even if
high-quality components are used. A
rusty exhaust pipe may go unnoticed
on a car, however, it detracts from the
overall appearance of a scooter. Fre-
quent 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 muffler outlet with a
plastic bag after the engine has
cooled down.
2. Make sure that all caps and covers
as well as all electrical couplers
and connectors, including the
spark plug cap, are tightly in-
stalled.
3. Remove extremely stubborn dirt,
like oil burnt onto the crankcase,
with a degreasing agent and a
brush, but never apply such prod-ucts onto seals, gaskets and wheel
axles. Always rinse the dirt and de-
greaser off with water.
Cleaning
CAUTION:

ECA10780

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 af-
fected area any longer than in-
structed. Also, thoroughly rinse
the area off with water, immedi-
ately dry it, and then apply a cor-
rosion protection spray.

Improper cleaning can damage
windshields, cowlings, panels
and other plastic parts. Use only
a soft, clean cloth or sponge
with mild detergent and water to
clean plastic.

Do not use any harsh chemical
products on plastic parts. Be
sure to avoid using cloths or
sponges which have been in
contact with strong or abrasive
cleaning products, solvent or

SCOOTER CARE AND STORAGE
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9thinner, fuel (gasoline), rust re-
movers or inhibitors, brake flu-
id, antifreeze or electrolyte.


Do not use high-pressure wash-
ers or steam-jet cleaners since
they cause water seepage and
deterioration in the following ar-
eas: seals (of wheel and swing-
arm bearings, fork and brakes),
electric components (couplers,
connectors, instruments,
switches and lights), breather
hoses and vents.

For scooters equipped with a
windshield: Do not use strong
cleaners or hard sponges as
they will cause dulling or
scratching. Some cleaning com-
pounds for plastic may leave
scratches on the windshield.
Test the product on a small hid-
den part of the windshield to
make sure that it does not leave
any marks. If the windshield is
scratched, use a quality plastic
polishing compound after
washing.
After normal use
Remove dirt with warm water, a mild
detergent, and a soft, clean sponge,
and then rinse thoroughly with clean
water. Use a toothbrush or bottlebrush
for hard-to-reach areas. Stubborn dirt
and insects will come off more easily if
the area is covered with a wet cloth for
a few minutes before cleaning.
After riding in the rain, near the sea oron salt-sprayed roadsSince sea salt or salt sprayed on the
roads during winter are extremely cor-
rosive in combination with water, carry
out the following steps after each ride in
the rain, near the sea or on
salt-sprayed roads.NOTE:

Salt sprayed on roads in the winter may
remain well into spring.
1. Clean the scooter with cold water
and a mild detergent after the en-
gine has cooled down.
CAUTION:

ECA10790
Do not use warm water since it in-
creases the corrosive action of the
salt.
2. Apply a corrosion protection spray
on all metal, including chrome- and
nickel-plated, surfaces to prevent
corrosion.
After cleaning
1. Dry the scooter with a chamois or
an absorbing cloth.
2. Use a chrome polish to shine
chrome, aluminum and stain-
less-steel parts, including the ex-
haust system. (Even the thermally
induced discoloring of stain-
less-steel exhaust systems can be
removed through polishing.)
3. To prevent corrosion, it is recom-
mended to apply a corrosion pro-
tection spray on all metal,
including chrome- and nickel-plat-
ed, surfaces.
4. Use spray oil as a universal clean-
er to remove any remaining dirt.
5. Touch up minor paint damage
caused by stones, etc.
6. Wax all painted surfaces.
7. Let the scooter dry completely be-
fore storing or covering it.

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WARNING

EWA10940

Make sure that there is no oil or
wax on the brakes or tires. If
necessary, clean the brake
discs and brake linings with a
regular brake disc cleaner or ac-
etone, and wash the tires with
warm water and a mild deter-
gent.

Before operating the scooter
test its braking performance
and cornering behavior.
CAUTION:

ECA10800

Apply spray oil and wax spar-
ingly and make sure to wipe off
any excess.

Never apply oil or wax to any
rubber and plastic parts, but
treat them with a suitable care
product.

Avoid using abrasive polishing
compounds as they will wear
away the paint.
NOTE:

Consult a Yamaha dealer for advice on
what products to use.
EAU36560
Storage
Short-term
Always store your scooter in a cool, dry
place and, if necessary, protect it
against dust with a porous cover.
CAUTION:

ECA10820

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. Fill up the fuel tank and add fuel
stabilizer (if available) to prevent
the fuel tank from rusting and the

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fuel from deteriorating.
3. Perform the following steps to pro-
tect 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

EWA10950
To prevent damage or injury from
sparking, make sure to ground the
spark plug electrodes while turning
the engine over.
4. Lubricate all control cables and thepivoting 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. 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
charge it. Store it in a cool, dry
place and charge it once a month.
Do not store the battery in an ex-
cessively 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
6-22.
NOTE:

Make any necessary repairs before
storing the scooter.

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89

SPECIFICATIONS
EAU2633J
Dimensions:
Overall 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:
115 mm (4.53 in)
Minimum turning radius:
1900 mm (74.8 in)
Weight:
With oil and fuel:
120.0 kg (265 lb)
Engine:
Engine type:
Air cooled 4-stroke, SOHC
Cylinder arrangement:
Forward-inclined single cylinder
Displacement:
125.0 cm
3

Bore
×
stroke:
52.4
×
57.9 mm (2.06
×
2.28 in)
Compression ratio:
10.00 :1
Starting system:
Electric starter and kickstarterLubrication system:
Wet sump

Engine oil:
Type:
SAE20W40
Recommended engine oil grade:
API service SG type or higher, JASO stan-
dard MA
Engine oil quantity:
Periodic oil change:
0.90 L (0.95 US qt) (0.79 Imp.qt)
Final transmission oil:
Type:
SAE10W30 type SE motor oil
Quantity:
0.11 L (0.12 US qt) (0.10 Imp.qt)
Air filter:
Air filter element:
Oil-coated paper element
Fuel:
Recommended fuel:
Regular unleaded gasoline onlyFuel tank capacity:
7.4 L (1.96 US gal) (1.63 Imp.gal)
Fuel injector:
Manufacturer:
AISAN
Model/quantity:
4P91 01 / 1
Spark plug (s):
Manufacturer/model:
NGK/CR7E
Spark plug gap:
0.7–0.8 mm (0.028–0.031 in)
Clutch:
Clutch type:
Dry, centrifugal automatic
Transmission:
Primary reduction system:
Helical gear
Primary reduction ratio:
38/13 (2.923)
Secondary reduction system:
Helical gear
Secondary reduction ratio:
40/12 (3.333)
Transmission type:
V-belt automatic
Operation:
Centrifugal automatic type
Chassis:
Frame type:
Steel tube backbone
Caster angle:
27.00 °
-20 -10 0
10 20 30
40
50 ˚C
SAE 10W-30
SAE 15W-40SAE 20W-40SAE 20W-50
SAE 10W-40

SPECIFICATIONS
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Trail:
90.0 mm (3.54 in)
Front tire:
Type:
Tubeless
Size:
110/70-12 47L
Manufacturer/model:
CHENG SHIN / C-992N
Rear tire:
Type:
Tubeless
Size:
120/70-12 58L
Manufacturer/model:
CHENG SHIN / C-6007
Maximum load:
172 kg (379 lb)
* (Total weight of rider, passenger, cargo
and accessories)
Tire air pressure (measured on cold
tires):
Loading condition:
0–90 kg (0–198 lb)
Front:
175 kPa (25 psi) (1.75 kgf/cm
2

)
Rear:
200 kPa (29 psi) (2.00 kgf/cm
2

)
Loading condition:
90–172 kg (198–379 lb)
Front:
200 kPa (29 psi) (2.00 kgf/cm
2

)Rear:
225 kPa (33 psi) (2.25 kgf/cm
2

)
Front wheel:
Wheel type:
Cast wheel
Rim size:
J12 X MT2.75
Rear wheel:
Wheel type:
Cast wheel
Rim size:
J12 X MT3.00
Front brake:
Type:
Single disc brake
Operation:
Right hand operation
Recommended fluid:
DOT 4
Rear brake:
Type:
Drum brake
Operation:
Left hand operation
Front suspension:
Type:
Telescopic fork
Spring/shock absorber type:
Coil spring/oil damper
Wheel travel:
78.0 mm (3.07 in)
Rear suspension:
Type:
Unit swing
Spring/shock absorber type:
Coil spring/oil damper
Wheel travel:
95.5 mm (3.76 in)
Electrical system:
Ignition system:
Transistorized coil ignition (digital)
Charging system:
AC magneto
Battery:
Model:
MF (YT7B-BS)
Voltage, capacity:
12 V, 6.5 Ah
Headlight:
Bulb type:
Halogen bulb
Bulb voltage, wattage
×
quantity:
Headlight:
12 V, 60 W/55.0 W
×
1
Tail/brake light:
12 V, 5.0 W/21.0 W
×
1
Front turn signal light:
12 V, 10.0 W
×
2
Rear turn signal light:
12 V, 10.0 W
×
2
Auxiliary light:
12 V, 5.0 W
×
2
License plate light:
12 V, 5.0 W
×
1