YAMAHA CYGNUS 125 2005 Service Manual

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PERIODIC MAINTENANCE AND MINOR REPAIR
EAUT1170
Checking the spark plugThe 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 char t. 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 included
in the owner’s tool kit.ZAUM00**1
1. Spark plug wrench
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 nec-
essary.
Specified spark plug:
CR7E (NGK)
To install the spark plug
1. Measure the spark plug gap with a
wire thickness gauge and, if nec-
essary, adjust the gap to specifi-
cation.
ZAUM00**
12(×4)
1. Panel B
2. ScrewTo install the panel
Place the panel in the original position,
and then install the screws.
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PERIODIC MAINTENANCE AND MINOR REPAIRZAUM00**
1
1. Spark plug gap
Spark plug gap:
0.6~0.7 mm (0.024~0.028 in)
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 tighten it to
the specified torque.
Tightening torque:
Spark plug:
13 Nm (1.3m  kgf, 9.4ft  lbf)
NOTE:
If a torque wrench is not available when
installing a spark plug, a good estimate
of the correct torque is 1/4~1/2 turn past
finger tight. However, the spark plug
should be tightened to the specified
torque as soon as possible.4. Install the spark plug cap.
5. Install the panel.
EAUT1350
Engine oil and oil strainerThe 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 changes from green
to red. The oil change indicator 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 centerstand.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 sev-
eral minutes, and then turn it off.
3. Wait a few minutes until the oil
settles, remove the oil filler cap,
wipe the dipstick clean, inser t it
back into the oil filler hole (without
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PERIODIC MAINTENANCE AND MINOR REPAIR
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.ZAUM00**
1
2
1. Maximum level mark
1. Minimum level mark4. 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 sev-
eral 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.
ECA10410
cCWhen removing the engine oil drain
bolt, the O-ring, spring, and oil
strainer will fall out. Take care not to
lose these parts.ZAUM00**
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1. Oil filler cap
ZAUM00**
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1. Engine oil drain bolt AZAUM00**
1
1. Engine oil drain bolt B4. 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
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PERIODIC MAINTENANCE AND MINOR REPAIR
and engine oil drain bolts, and then
tighten the drain bolts to the speci-
fied torque.
Tightening torque:
Engine oil drain bolt A:
20 Nm (2.0 m  kgf, 14.5ft  lbf)
Engine oil drain bolt B:
20 Nm (2.0 m  kgf, 14.5 ft  lbf)
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 filler
cap.
Recommended engine oil:
See page 8-1.
Oil change quantity:
0.9 L (0.98 US qt) (0.83 Imp.qt)
ECA11670
cC8 88 8
8Do not use oils with a diesel
specification of “CD” or oils of a
higher quality than specified. Inaddition, do not use oils labeled
“ENERGY CONSERVING II” or
higher.
8 88 8
8Be 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,
immediately turn the engine off and
check for the cause.
9. Turn the engine off, and then check
the oil level and correct it if neces-
sary.
10. Reset the oil change indicator. (See
page 3-2 for reset procedures.)NOTE:
If the engine oil is changed before the
oil change indicator changes to red (i.e.
before the periodic oil change interval
has been reached), the indicator must
be reset after the oil change for the next
periodic oil change to be indicated at the
correct time.
EAU20060
Final transmission oilThe 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 transmission oil must
be changed as follows at the intervals
specified in the periodic maintenance
and lubrication chart.
1. Start the engine, warm it up by
riding the scooter for several min-
utes, and then stop the engine.
2. Place the scooter on the
centerstand.
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.
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PERIODIC MAINTENANCE AND MINOR REPAIR
ZAUM00**
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1. Final transmission oil filler cap5. Install the final transmission oil
drain bolt, and then tighten it to the
specified torque.ZAUM00**
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1. Final transmission oil drain bolt
Tightening torque:
Final transmission oil drain bolt:
23 Nm (2.3 m  kgf, 16.6 ft  lbf)
6. Add the specified amount of the
recommended final transmission
oil, and then install and tighten the
oil filler cap.
Recommended final transmission
oil:
See page 8-1.
Oil quantity:
0.13 L (0.14 US qt) (0.1 Imp.qt)
EWA11310
w8 88 8
8Make sure that no foreign mate-
rial enters the final transmission
case.
8 88 8
8Make 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.
EAUT1341
Air filter and V-belt case air fil-
ter elementsThe air filter and V-belt case air filter el-
ements should be cleaned at the inter-
vals specified in the periodic mainte-
nance and lubrication chart. Clean both
filter elements more frequently if you are
riding in unusually wet or dusty areas.
Cleaning the air filter element
1. Place the scooter on the
centerstand.
2. Remove the air filter case cover by
removing the screws.ZAUM00**
2(×6)
1
1. Air filter case cover
2. Screw3. Pull the air filter element out, and
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PERIODIC MAINTENANCE AND MINOR REPAIR
then blow the dirt out with com-
pressed air as shown.
ZAUM00**
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1. Air filter element4. Check the air filter element for dam-
age and replace it if necessary.
5. Insert the air filter element into the
air filter case.
ECA10480
cC8 88 8
8Make sure that the air filter ele-
ment is properly seated in the air
filter case.
8 88 8
8The 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
installing the screws.
Cleaning the V-belt case air filter ele-
ment
1. Remove the V-belt air filter case
cover by removing the screws.ZAUM00**
21
1. Air filter case cover
2. Screw2. Remove the filter element holder by
removing the screw.
ZAUM00**
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1. Air filter element holder3. Pull the air filter element out, and
then clean it with solvent. After
cleaning, remove the remaining
solvent by squeezing the element.
EWA10430
wUse 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.
ECA10520
cCTo avoid damaging the air filter ele-
ment, handle it gently and carefully,
and do not twist it.
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PERIODIC MAINTENANCE AND MINOR REPAIR
ZAUM00**
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1. V-belt case air filter element4. 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.
Recommended oil:
Engine oil
5. Insert the element into the air filter
case.
6. Install the filter element holder by
installing the screw.
EAU21300
Adjusting the carburetorThe carburetor is an important part of
the engine and requires very sophisti-
cated adjustment. Therefore, all carbu-
retor adjustments should be left to a
Yamaha dealer, who has the necessary
professional knowledge and experience. 7. Install the V-belt air filter case cover
by installing the screws.
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PERIODIC MAINTENANCE AND MINOR REPAIR
EAU21370
Adjusting the throttle cable
free playThe throttle cable free play should mea-
sure 3~5 mm (0.12~0.20 in) at the
throttle grip. Periodically check the
throttle cable free play and, if necessary,
adjust it as follows.NOTE:
The engine idling speed must be cor-
rectly adjusted before checking and ad-
justing the throttle cable free play.1. Loosen the locknut.
2. To increase the throttle cable free
play, turn the adjusting nut in direc-
tion (a). To decrease the throttle
cable free play, turn the adjusting
nut in direction (b).
ZAUM00**
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(a)
(b)
1. Locknut
1. Adjusting nut3. Tighten the locknut.
EAU21401
Valve clearanceThe 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 in-
tervals specified in the periodic mainte-
nance and lubrication chart.
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PERIODIC MAINTENANCE AND MINOR REPAIR
EAU33600
TiresTo 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.
EWA10500
w8 88 8
8The tire air pressure must be
checked and adjusted on cold
tires (i.e., when the temperature
of the tires equals the ambient
temperature).
8 88 8
8The tire air pressure must be
adjusted in accordance with the
riding speed and with the total
weight of rider, passenger, cargo,
and accessories approved for this
model.
Tire air pressure (measured on cold
tires):
0~90 kg (0~198 lb):
Front:
175 kPa (26 psi) (1.75 kgf/cm
2)
Rear:
200 kPa (29 psi) (2.0 kgf/cm2)
90~170 kg (198~419 lb) to maxi-
mum load:
Front:
200 kPa (29 psi) (2.0 kgf/cm2)
Rear:
225 kPa (33 psi) (2.25 kgf/cm2)
Maximum load*:
170 kg (374 lb)
* Total weight of rider, passenger,
cargo and accessories
EWA11200
wBecause loading has an enormous
impact on the handling, braking, per-
formance and safety characteristics
of your vehicle, you should keep the
following precautions in mind.
8 88 8
8NEVER OVERLOAD THE VE-
HICLE! Operation of an over-
loaded motorcycle may result in
tire damage, loss of control, orsevere injury. Make sure that the
total weight of rider, passenger,
cargo, and accessories does not
exceed the specified maximum
load for the vehicle.
8 88 8
8Do 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.
8 88 8
8Adjust the tire air pressure with
regard to the load.
Check the tire condition and air
pressure before each ride.
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PERIODIC MAINTENANCE AND MINOR REPAIRTire inspectionZAUM00**
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1. Tire tread depth
2. Tire sidewallThe tires must be checked before each
ride. 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.
Minimum tire tread depth (front and
rear):
1.6 mm (0.06 in)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.
Front tire:
Size:
110 / 70-12 47L
Manufacturer/model:
CHENG SHIN
Rear tire:
Size:
120 / 70-12 58L
Manufacturer/model:
CHENG SHIN
EWA10470
w8 88 8
8Have a Yamaha dealer replace
excessively worn tires. Besides
being illegal, operating the ve-
hicle with excessively worn tires
decreases riding stability and
can lead to loss of control.
8 88 8
8The replacement of all wheel and
brake related parts, including the
tires, should be left to a Yamaha
dealer, who has the necessaryprofessional knowledge and ex-
perience.
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