2007 YAMAHA CYGNUS 125 engine

PERIODIC MAINTENANCE AND MINOR REPAIR
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EAUT1843
Air filter and V-belt case air
filter elements
The air filter and V-belt case air filter el-
ements should be cleaned at the inter-
vals specified in the periodic
maintenance and lubrication chart.
Clean both filter elements more fre-
quently if you are riding in unusually
wet or dusty areas. The air filter check
hoses must be frequently checked and
cleaned if necessary.
Cleaning the air filter element
1. Place the scooter on the center-
stand.
2. Remove the air filter case cover by
removing the screws.3. Pull the air filter element out, and
then blow the dirt out with com-
pressed air as shown.
4. Check the air filter element fordamage and replace it if neces-
sary.
5. Insert the air filter element into the
air filter case.
CAUTION:

ECA10480

Make sure that the air filter ele-
ment is properly seated in the
air filter case.

The engine should never be op-
erated without the air filter ele-
ment installed, otherwise the
piston(s) and/or cylinder(s) may
become excessively worn.
6. Install the air filter case cover by in-
stalling the screws.
Cleaning the air filter check hoses
1. Check the hoses on the front and
rear side of the air filter case for ac-
cumulated dirt or water.
2. If dirt or water is visible, remove
the hoses, clean them, and then
install them.
Cleaning the V-belt case air filter el-
ement
1. Remove the V-belt air filter case

1. Air filter case cover
2. Screw
3. Air filter check hose
1. Air filter element
ZAUM00**
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ZAUM00**
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EAU21382
Checking the throttle cable
free play
The throttle cable free play should mea-
sure 3.0–5.0 mm (0.12–0.20 in) at the
throttle grip. Periodically check the
throttle cable free play and, if neces-
sary, have a Yamaha dealer adjust it.
EAU21401
Valve clearance
The 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.
EAUT2140
Tires
To maximize the performance, durabil-
ity, and safe operation of your vehicle,
note the following points regarding the
specified tires.
Tire air pressure
The tire air pressure should be checked
and, if necessary, adjusted before each
ride.
WARNING

EWA10500

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 ad-
justed in accordance with the
riding speed and with the total
weight of rider, passenger, car-
go, and accessories approved
for this model.
1. Throttle cable free play
ZAUM00**
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PERIODIC MAINTENANCE AND MINOR REPAIR
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check the cause.

EAU22720
Changing the brake fluid
Have a Yamaha dealer change the
brake fluid at the intervals specified in
the NOTE after the periodic mainte-
nance and lubrication chart. In addition,
have the oil seals of the brake master
cylinder and caliper as well as the
brake hose replaced at the intervals
listed below or whenever they are dam-
aged or leaking.

Oil seals: Replace every two
years.

Brake hose: Replace every four
years.
EAU23100
Checking and lubricating the
cables
The operation of all control cables and
the condition of the cables should be
checked before each ride, and the ca-
bles and cable ends should be lubricat-
ed if necessary. If a cable is damaged
or does not move smoothly, have a
Yamaha dealer check or replace it.
WARNING

EWA10720
Damage to the outer sheath may in-
terfere with proper cable operation
and will cause the inner cable to
rust. Replace a damaged cable as
soon as possible to prevent unsafe
conditions.
Recommended lubricant:
Engine oil

PERIODIC MAINTENANCE AND MINOR REPAIR
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EAU23271
Checking the front fork
The condition and operation of the front
fork must be checked as follows at the
intervals specified in the periodic main-
tenance and lubrication chart.
To check the condition
WARNING

EWA10750
Securely support the vehicle so that
there is no danger of it falling over.
Check the inner tubes for scratches,
damage and excessive oil leakage.
To check the operation
1. Place the vehicle on a level sur-
face and hold it in an upright posi-
tion.
2. While applying the front brake,
push down hard on the handlebars
several times to check if the front
fork compresses and rebounds
smoothly.
CAUTION:

ECA10590
If any damage is found or the front
fork does not operate smoothly,
have a Yamaha dealer check or re-
pair it.
EAU23280
Checking the steering
Worn or loose steering bearings may
cause danger. Therefore, the operation
of the steering must be checked as fol-
lows at the intervals specified in the pe-
riodic maintenance and lubrication
chart.
1. Place a stand under the engine to
raise the front wheel off the
ground.
WARNING

EWA10750
Securely support the vehicle so that
there is no danger of it falling over.
2. Hold the lower ends of the front
fork legs and try to move them for-
ward and backward. If any free
play can be felt, have a Yamaha
dealer check or repair the steering.
ZAUM00**

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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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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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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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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