YAMAHA CYGNUS 125 2007 Service Manual

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EAU18771
Removing and installing
panels
The panels shown need to be removed
to perform some of the maintenance
jobs described in this chapter. Refer to
this section each time a panel needs to
be removed and installed.
EAUT1882
Panel A
To remove the panel
Remove the screws, and then take thepanel off.
To install the panel
Place the panel in the original position,
and then install the screws.
Panel B
To remove the panelRemove the screws, and then take the
panel off.To install the panel
Place the panel in the original position,
and then install the screws.
Panel C
To remove the panelRemove the screws, and then take the
panel off.

1. Panel A
2. Panel B
3. Panel C
4. Panel D
ZAUM00**
12
3 4

1. Panel A
2. Screw
ZAUM00**
1
2✕(8)

1. Panel B
2. Screw
ZAUM00**1
2✕(2)

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To install the panel
Place the panel in the original position,
and then install the screws.
Panel D
To remove the panel1. Open the seat. (See page 3-9.)2. Remove the quick fasteners by
pushing in the center pin, and then
take the panel off.
To install the panel
Place the panel in the original position,
and then install quick fasteners.

EAUT1830
Checking the spark plug
The 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 mainte-
nance and lubrication chart. In addition,
the condition of the spark plug can re-
veal the condition of the engine.
To remove the spark plug
1. Remove panel C. (See page 6-6.)
2. Remove the spark plug cap.
3. Remove the spark plug as shown,
with the spark plug wrench includ-
ed in the owner’s tool kit.
1. Panel C
2. Screw
ZAUM00**
2(✕4)
1

1. Panel D
2. Screw
ZAUM00**
2
1

1. Spark plug wrench
ZAUM00**
1

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9 To check the spark plug
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 vehicle is
ridden normally).
NOTE:

If the spark plug shows a distinctly dif-
ferent color, the engine could be defec-
tive. Do not attempt to diagnose such
problems yourself. Instead, have a
Yamaha dealer check the vehicle.
2. Check the spark plug for electrode
erosion and excessive carbon or
other deposits, and replace it if
necessary.
To install the spark plug
1. Measure the spark plug gap with a
wire thickness gauge and, if nec-
essary, adjust the gap to specifica-
tion.2. Clean the surface of the spark plug
gasket and its mating surface, and
then wipe off any grime from the
spark plug threads.
3. Install the spark plug with the
spark plug wrench, and then tight-
en it to the specified torque.
NOTE:

If a torque wrench is not available when
installing a spark plug, a good estimateof the correct torque is 1/4–1/2 turn
past finger tight. However, the spark
plug should be tightened to the speci-
fied torque as soon as possible.
4. Install the spark plug cap.
5. Install the panel.
Specified spark plug:
NGK/CR7E
1. Spark plug gap
Spark plug gap:
0.7–0.8 mm (0.028–0.031 in)
Tightening torque:
Spark plug:
13 Nm (1.3 m·kgf, 9.4 ft·lbf)
ZAUM00**
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EAUT1351
Engine oil and oil strainer
The engine oil level should be checked
before each ride. In addition, the oil
must be changed and the oil strainer
cleaned at the intervals specified in the
periodic maintenance and lubrication
chart. The engine oil must also be
changed at the initial 1000 km (600 mi)
and when the oil change indicator flash-
es. The oil change tripmeter must be
reset after the initial 1000 km (600 mi).
(See page 3-2 for reset procedures.)
To check the engine oil level
1. Place the vehicle on the center-
stand.
NOTE:

Make sure that the vehicle is positioned
straight up when checking the oil level.
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 oil filler cap, wipe
the dipstick clean, insert it backinto the oil filler hole (without
screwing it in), and then remove it
again to check the oil level.
NOTE:

The 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. Insert the dipstick into the oil filler
hole, and then tighten the oil filler
cap.
To change the engine oil and clean
the oil strainer
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
and drain bolts to drain the oil from
the crankcase.
CAUTION:

ECA10410
When removing the engine oil drain
bolt, the O-ring, spring, and oil
strainer will fall out. Take care not to
lose these parts.
1. Maximum level mark
2. Minimum level mark
ZAUM00**
12

1. Oil filler cap
ZAUM00**
1

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4. Clean the oil strainer with solvent,
and then check it for damage and
replace it if necessary.
5. Check the O-ring for damage and
replace it if necessary.
6. Install the oil strainer, spring,O-ring and engine oil drain bolts,
and then tighten the drain bolts to
the specified torque.
NOTE:

Make sure that the O-ring is properly
seated.
7. Add the specified amount of the
recommended engine oil, and then
install and tighten the engine oil fill-
er cap.
CAUTION:

ECA11670

Do not use oils with a diesel
specification of “CD” or oils of a
higher quality than specified. In
addition, do not use oils labeled
“ENERGY CONSERVING II” orhigher.

Be sure no foreign material en-
ters the crankcase.
8. Start the engine, and then let it idle
for several minutes while checking
it for oil leakage. If oil is leaking, im-
mediately turn the engine off and
check for the cause.
9. Turn the engine off, and then
check the oil level and correct it if
necessary.
10. Reset the oil change tripmeter.
(See page 3-2 for reset proce-
dures.)
NOTE:

If the engine oil is changed before the
oil change indicator flashes (i.e. before
the periodic oil change interval has
been reached), the oil change tripmeter
must be reset after the oil change for
the next periodic oil change to be indi-
cated at the correct time.
1. Engine oil drain bolt A
1. Engine oil drain bolt B
ZAUM00**
1
ZAUM00**
1

Tightening torque:
Engine oil drain bolt A:
20 Nm (2.0 m·kgf, 14.5 ft·lbf)
Engine oil drain bolt B:
20 Nm (2.0 m·kgf, 14.5 ft·lbf)
Recommended engine oil:
See page 8-1.
Oil change quantity:
0.90 L (0.95 US qt) (0.79 Imp.qt)

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EAU20061
Final transmission oil
The final 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 final transmis-
sion oil must be changed as follows at
the intervals specified in the periodic
maintenance and lubrication chart.
1. Start the engine, warm up the final
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 final
transmission case to collect the
used oil.
4. Remove the oil filler cap and drain
bolt to drain the oil from the final
transmission case.5. Install the final transmission oil
drain bolt, and then tighten it to the
specified torque.6. Add the specified amount of the
recommended final transmission
oil, and then install and tighten the
oil filler cap.
WARNING

EWA11310

Make sure that no foreign mate-
rial enters the final transmission
case.

Make sure that no oil gets on the
tire or wheel.
7. Check the final transmission case
for oil leakage. If oil is leaking,
check for the cause.
1. Final transmission oil filler cap
1. Final transmission oil drain bolt
Tightening torque:
Final transmission oil drain bolt:
23 Nm (2.3 m·kgf, 16.6 ft·lbf)
ZAUM00**
1
ZAUM00**
1

Recommended final transmission
oil:
See page 8-1.
Oil quantity:
0.11 L (0.12 US qt) (0.10 Imp.qt)

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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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3
3
ZAUM00**
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cover by removing the screws.
2. Remove the filter element holder
by removing the screw.
3. Pull the air filter element out, and
then clean it with solvent. After
cleaning, remove the remainingsolvent by squeezing the element.
WARNING

EWA10430
Use only a dedicated parts cleaning
solvent. To avoid the risk of fire or
explosion, do not use gasoline or
solvents with a low flash point.
CAUTION:

ECA10520
To avoid damaging the air filter ele-
ment, handle it gently and carefully,
and do not twist it.
4. Apply oil of the recommended type
to the entire surface of the sponge
material, and then squeeze the ex-
cess oil out.
NOTE:

The air filter element should be wet but
not dripping.
5. Insert the element into the air filter
case.
6. Install the filter element holder by
installing the screw.
7. Install the V-belt air filter case cov-
er by installing the screws.
1. V-belt air filter case cover
1. Air filter element holder
ZAUM00**
1
ZAUM00**
1

1. V-belt case air filter element
ZAUM00**
1

Recommended oil:
Yamaha foam air filter oil or other
quality foam air filter oil

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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
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WARNING

EWA11200
Because loading has an enormous
impact on the handling, braking,
performance and safety characteris-
tics of your vehicle, you should keep
the following precautions in mind.

NEVER OVERLOAD THE VEHI-
CLE! Operation of an overload-
ed vehicle may result in tire
damage, loss of control, or se-
vere injury. Make sure that the
total weight of rider, passenger,
cargo, and accessories doesnot exceed the specified maxi-
mum load for the vehicle.

Do not carry along loosely
packed items, which can shift
during a ride.

Securely pack the heaviest
items close to the center of the
vehicle and distribute the
weight evenly on both sides.

Adjust the tire air pressure with
regard to the load.

Check the tire condition and air
pressure before each ride.
Tire inspection
The tires must be checked before eachride. If the center tread depth reaches
the specified limit, if the tire has a nail or
glass fragments in it, or if the sidewall is
cracked, have a Yamaha dealer re-
place the tire immediately.
NOTE:

The tire tread depth limits may differ
from country to country. Always comply
with the local regulations.
Tire information
This model is equipped with tubeless
tires.
Tire air pressure (measured on cold
tires):
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

)
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

)
Maximum load*:
172 kg (379 lb)
* Total weight of rider, passenger, car-
go and accessories
1. Tire tread depth
2. Tire sidewall
ZAUM00**
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2
Minimum tire tread depth (front and
rear):
0.8 mm (0.03 in)
Front tire:
Size:
110/70-12 47L
Manufacturer/model:
CHENG SHIN / C-992N
Rear tire:
Size:
120/70-12 58L
Manufacturer/model:
CHENG SHIN / C-6007