2005 YAMAHA CYGNUS 125 engine

6-8
1
2
3
4
5
6
7
8
9
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
5ML-F8199-E1ch6.pmd2004/10/04, 20:08 8

6-9
1
2
3
4
5
6
7
8
9
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**
1
1. Oil filler cap
ZAUM00**
1
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
5ML-F8199-E1ch6.pmd2004/10/04, 20:08 9

6-10
1
2
3
4
5
6
7
8
9
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.
5ML-F8199-E1ch6.pmd2004/10/04, 20:08 10

6-12
1
2
3
4
5
6
7
8
9
PERIODIC MAINTENANCE AND MINOR REPAIR
then blow the dirt out with com-
pressed air as shown.
ZAUM00**
1
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**
1
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.
5ML-F8199-E1ch6.pmd2004/10/04, 20:08 12

6-13
1
2
3
4
5
6
7
8
9
PERIODIC MAINTENANCE AND MINOR REPAIR
ZAUM00**
1
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.
5ML-F8199-E1ch6.pmd2004/10/04, 20:08 13

6-14
1
2
3
4
5
6
7
8
9
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**
1
2
(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.
5ML-F8199-E1ch6.pmd2004/10/04, 20:08 14

6-20
1
2
3
4
5
6
7
8
9
PERIODIC MAINTENANCE AND MINOR REPAIR
EAU22720
Changing the brake fluidHave a Yamaha dealer change the brake
fluid at the intervals specified in the
NOTE after the periodic maintenance
and lubrication chart. In addition, have
the oil seals of the brake master cylin-
der and caliper as well as the brake hose
replaced at the intervals listed below or
whenever they are damaged or leaking.
8Oil seals: Replace every two years.
8Brake hose: Replace every four
years.
EAU23100
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 lubri-
cated if necessary. If a cable is dam-
aged or does not move smoothly, have
a Yamaha dealer check or replace it.
Recommended lubricant:
Engine oil
EWA10720
wDamage 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 condi-
tions.
8As the brake pads wear, it is nor-
mal for the brake fluid level to
gradually go down. However, if the
brake fluid level goes down sud-
denly, have a Yamaha dealer check
the cause.
5ML-F8199-E1ch6.pmd2004/10/04, 20:08 20

6-22
1
2
3
4
5
6
7
8
9
PERIODIC MAINTENANCE AND MINOR REPAIR
EAU23271
Checking the front forkThe 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
EWA10750
wSecurely support the motorcycle 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 motorcycle 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 sev-
eral times to check if the front fork
compresses and rebounds
smoothly.
ZAUM00**
ECA10590
cCIf any damage is found or the front
fork does not operate smoothly, have
a Yamaha dealer check or repair it.
EAU23280
Checking the steeringWorn 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
periodic maintenance and lubrication
chart.
1. Place a stand under the engine to
raise the front wheel off the ground.
EWA10750
wSecurely support the motorcycle 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 forward
and backward. If any free play can
be felt, have a Yamaha dealer check
or repair the steering.
5ML-F8199-E1ch6.pmd2004/10/04, 20:08 22