engine YAMAHA SR125 2000 Owner's Manual

PERIODIC MAINTENANCE AND MINOR REPAIR
6-11
6
EAU00629
Carburetor adjustmentThe carburetor is a vital part of the en-
gine and requires very sophisticated
adjustment. Most adjustments should
be left to a Yamaha dealer who has the
professional knowledge and experi-
ence to do so. However, the following
may be serviced by the owner as part
of routine maintenance.
EC000094
CAUTION:@ The carburetor was set at the
Yamaha factory after many tests. If
the settings are changed, poor en-
gine performance and damage may
result. @
EAU01168
Idle speed adjustmentNOTE:@ A diagnostic tachometer must be used
for this procedure. @1. Attach the tachometer. Start the
engine and warm it up for a few
minutes at approximately 1,000 to
2,000 r/min. Occasionally rev the
engine to 4,000 to 5,000 r/min.
The engine is warm when it quick-
ly responds to the throttle.2. Set the idle to the specified engine
speed by adjusting the throttle
stop screw. Turn the screw in di-
rection
a to increase engine
speed and in direction
b to de-
crease engine speed.
NOTE:@ If the specified idle speed cannot be
obtained by performing the above ad-
justment, consult a Yamaha dealer. @1. Throttle stop screwStandard idle speed:
1,300 ~ 1,400 r/min
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PERIODIC MAINTENANCE AND MINOR REPAIR
6-12
6
EAU00634
Throttle cable free play
adjustmentNOTE:@ Before checking the throttle cable free
play, the engine idling speed should be
adjusted. @Adjust the throttle cable by turning the
adjusting nut so that specified free play
at the throttle grip is obtained.1. Loosen the locknut.
2. Turn the adjusting nut in
direction
a to increase free play
and in direction
b to decrease
free play.
3. Tighten the locknut.
EAU00636
Cam chain adjustmentThe cam chain becomes loose with
use, resulting in improper valve timing
and engine noise. To prevent this, the
cam chain tensioner must be adjusted
regularly. This adjustment, however,
should be left to a professional
Yamaha service technician.
a. Free playFree play:
3 ~ 5 mm
1. Adjusting nut
2. Locknut
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PERIODIC MAINTENANCE AND MINOR REPAIR
6-13
6
EAU00637
Valve clearance adjustmentThe correct valve clearance changes
with use, resulting in improper fuel/air
supply or engine noise. To prevent this,
the valve clearance must be adjusted
regularly. This adjustment however,
should be left to a professional
Yamaha service technician.
EAU00647
TiresTo ensure maximum performance,
long service, and safe operation, note
the following:
Tire air pressure
Always check and adjust the tire pres-
sure before operating the motorcycle.
EW000082
WARNING
@ Tire inflation pressure should be
checked and adjusted when the
temperature of the tire equals the
ambient air temperature. Tire infla-
tion pressure must be adjusted ac-
cording to total weight of cargo,
rider, passenger, and accessories
(fairing, saddlebags, etc. if approved
for this model), and vehicle speed. @
CE-32EMaximum load* 160 kg
Cold tire pressure Front Rear
Up to 90 kg*175 kPa
(1.75 kg/cm
2,
1.75 bar)200 kPa
(2.00 kg/cm
2,
2.00 bar)
90 kg load ~
Maximum load*175 kPa
(1.75 kg/cm
2,
1.75 bar)225 kPa
(2.25 kg/cm
2,
2.25 bar)
* Load is the total weight of cargo, rider, passenger
and accessories.
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PERIODIC MAINTENANCE AND MINOR REPAIR
6-22
6
EAU01533
Drive chain slack adjustment1. Loosen the rear brake adjusting
nut.
2. Loosen the wheel axle nut.3. To tighten the chain, turn the chain
adjusting plates in direction
a.
To loosen the chain, turn the chain
adjusting plates in direction
b and
push the wheel forward. Turn each
chain adjusting plate to exactly the
same position to maintain correct
axle alignment.
EC000096
CAUTION:@ Too little chain slack will overload
the engine and other vital parts.
Keep the slack within the specified
limits. @
4. Tighten the wheel axle nut to the
specified torque.
5. Adjust the brake pedal free play.
EW000103
WARNING
@ Check the operation of the brake
light after adjusting the rear brake. @
1. Adjusting nut
1. Axle nut
2. Chain adjusting plate
Tightening torque:
Wheel axle nut:
65 Nm (6.5 m·kg)
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PERIODIC MAINTENANCE AND MINOR REPAIR
6-23
6
EAU01106*
Drive chain lubricationThe chain consists of many parts which
work with each other. If the chain is not
maintained properly, it will wear out
quickly. Therefore, the chain must be
serviced regularly. This service is es-
pecially necessary when riding in dusty
areas.
The drive chain should be lubricated
every 500 km. First, remove all dirt and
mud from the chain with a brush or
cloth. Then, spray any of the many
brands of spray-type chain lubricant
between both rows of side plates and
on all center rollers.
To clean the chain thoroughly, remove
it from the motorcycle, dip it in solvent,
and clean out as much dirt as possible.
Then, take the chain out of the solvent
to dry it, and immediately lubricate it to
prevent it from rusting.
EAU02962
Cable inspection and
lubrication
EW000112
WARNING
@ Damage to the outer housing of ca-
bles may lead to internal rusting and
interfere with the cable movement.
Replace damaged cables as soon as
possible to prevent unsafe condi-
tions. @Lubricate the cables and cable ends. If
a cable does not operate smoothly, ask
a Yamaha dealer to replace it.
EAU00773
Throttle cable and grip
lubricationThe throttle twist grip assembly should
be greased at the time that the cable is
lubricated, since the grip must be re-
moved to get at the end of the throttle
cable. After removing the screws, hold
the end of the cable up in the air and
put in several drops of lubricant. With
the throttle grip disassembled, coat the
metal surface of the grip assembly with
a suitable all-purpose grease.
Recommended lubricant:
Engine oil
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PERIODIC MAINTENANCE AND MINOR REPAIR
6-24
6
EAU02984
Brake and shift pedal
lubricationLubricate the pivoting parts.
EAU02985
Brake and clutch lever
lubricationLubricate the pivoting parts.
EAU02965
Center and sidestand
lubricationLubricate the pivoting and mating
joints.
Check to see that the center and side-
stand move up and down smoothly. Recommended lubricant:
Engine oil
Recommended lubricant:
Engine oil
Recommended lubricant:
Engine oil
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PERIODIC MAINTENANCE AND MINOR REPAIR
6-26
6
EAU00794
Steering inspectionPeriodically inspect the condition of the
steering. Worn out or loose steering
bearings may be dangerous. Place a
stand under the engine to raise the
front wheel off the ground. Hold the
lower end of the front forks and try to
move them forward and backward. If
any free play can be felt, ask a Yamaha
dealer to inspect and adjust the steer-
ing. Inspection is easier if the front
wheel is removed.
EW000115
WARNING
@ Securely support the motorcycle so
there is no danger of it falling over. @
EAU01144
Wheel bearingsIf there is play in the front or rear wheel
hub or if the wheel does not turn
smoothly, have a Yamaha dealer in-
spect the wheel bearings.
EAU01647
BatteryRemove panel A. (See page 6-5 for re-
moval and installation procedures.)
Check the level of the battery electro-
lyte and make sure that the terminals
are tight. Fill with distilled water if the
electrolyte level is low.1. Maximum level mark
2. Minimum level mark
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PERIODIC MAINTENANCE AND MINOR REPAIR
6-34
6
EAU03009
Troubleshooting chart
EW000125
WARNING
@ Never check the fuel system while smoking or in the vicinity of an open flame. @
Check if there is fuel in
the fuel tank.1. Fuel
Enough fuel.
No fuel.
Go to compression check.
Supply fuel.
Engine doesn’t start, go to compression check.
Use the electric starter.2. Compression
There is compression.
No compression.
Go to ignition check.
Ask a Yamaha dealer to
inspect.
Remove spark plug and
check electrodes.3. Ignition
Wet.
Dry.
Wipe clean with dry cloth and correct
spark gap or replace spark plug.
Ask a Yamaha dealer to inspect.
Engine doesn’t start, ask a Yamaha
dealer to inspect.Engine doesn’t start, go to battery
check.Open throttle half-way and start
the engine.
Use the electric starter.4. Battery
Engine turns over
quickly.
Engine turns over
slowly.
Battery good.Check fluid, recharge,
check connections.
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MOTORCYCLE CARE AND STORAGE
7-3
7 After riding in the rain, near the sea or
on salt-sprayed roadsSince sea salt or salt sprayed on the
roads in the winter are extremely corro-
sive in combination with water, carry
out the following steps after each ride
in the rain, near the sea or on salt-
sprayed roads. (Salt sprayed in the
winter may remain on the roads well
into spring.)
1. Clean your motorcycle with cold
water and soap after the engine
has cooled down.
ECA00012
CAUTION:@ Do not use warm water since it in-
creases the corrosive action of the
salt. @2. Be sure to apply a corrosion pro-
tection spray on all (even chrome-
and nickel-plated) metal surfaces
to prevent corrosion.After cleaning
1. Dry the motorcycle with a chamois
or an absorbing cloth.
2. Immediately dry the drive chain
and lubricate it to prevent it from
rusting.
3. Use a chrome polish to shine
chrome, aluminum and stainless-
steel parts, including the exhaust
system. (Even the thermally in-
duced discoloring of stainless-
steel exhaust systems can be re-
moved through polishing.)
4. To prevent corrosion, it is recom-
mended to apply a corrosion pro-
tection spray on all (even chrome-
and nickel-plated) metal surfaces.
5. Use spray oil as a universal clean-
er to remove any remaining dirt.
6. Touch up minor paint damage
caused by stones, etc.
7. Wax all painted surfaces.
8. Let the motorcycle dry completely
before storing it or covering it.
EWA00001
WARNING
@ Make sure that there is no oil or wax
on the brakes and tires. If neces-
sary, clean the brake discs and lin-
ings with a regular brake disc
cleaner or acetone, and wash the
tires with warm water and mild soap.
Then, carefully test the motorcycle
for its braking performance and cor-
nering behavior. @
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MOTORCYCLE CARE AND STORAGE
7-5
7 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 place the spark
plug on the cylinder head so that
the electrodes are grounded. (This
will limit sparking 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, install the spark
plug and then the spark plug cap.
EWA00003
WARNING
@ When turning the engine over, be
sure to ground the spark plug elec-
trodes to prevent damage or injury
from sparking. @
6. Lubricate all control cables and
the pivoting points of all levers and
pedals as well as of the sidestand/
centerstand.
7. Check and, if necessary, correct
the tire air pressure, then raise the
motorcycle 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.
8. Cover up the muffler outlet with a
plastic bag to prevent moisture
from entering.9. Remove the battery and fully
charge it. Store it in a cool, dry
place and recharge it once a
month. Do not store the battery in
an excessively cold or warm place
(less than 0 °C or more than
30 °C). For more information, see
“Battery storage” in the chapter
“PERIODIC MAINTENANCE AND
MINOR REPAIRS”.
NOTE:@ Make any necessary repairs before
storing the motorcycle. @
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