2007 YAMAHA TTR90 engine

PERIODIC MAINTENANCE AND MINOR REPAIR
6-9
6 To change the engine oil
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 bolt to drain the oil from
the crankcase.
4. Install the engine oil drain bolt, and
then tighten it to the specified
torque.5. Add the specified amount of the
recommended engine oil, and then
install and tighten the engine oil fill-
er cap.
CAUTION:
ECA11620


In order to prevent clutch slip-
page (since the engine oil also
lubricates the clutch), do not
mix any chemical additives. Do
not use oils with a diesel speci-
fication of “CD” or oils of a high-
er quality than specified. In
addition, do not use oils labeled
“ENERGY CONSERVING II” or
higher.


Make sure that no foreign mate-rial enters the crankcase.
6. 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.7. Turn the engine off, and then
check the oil level and correct it if
necessary.
1. Engine oil drain boltTightening torque:
Engine oil drain bolt:
20 Nm (2.0 m·kgf, 14 ft·lbf)
Recommended engine oil:
See page 8-1.
Oil change quantity:
0.80 L (0.85 US qt) (0.70 Imp.qt)
U3P281E0.book Page 9 Monday, April 17, 2006 11:26 AM

PERIODIC MAINTENANCE AND MINOR REPAIR
6-11
6
CAUTION:
ECA15571


Make sure that the mesh and the
sponge material are properly
seated in the air filter case.


The engine should never be op-
erated without the mesh and the
sponge material installed, oth-
erwise the piston(s) and/or cyl-
inder(s) may becomeexcessively worn.
8. Install the air filter case cover by in-
stalling the screws.
NOTE:Make sure that the spark plug cable isrouted as shown.9. Install the panel.
To clean the air filter check hose
1. Check the hoses at the bottom of
the air filter case for accumulated
dirt or water.2. If dirt or water is visible, remove
the hoses, clean them, and then
reinstall them.1. Spark plug cable
1. Air filter check hose
1
U3P281E0.book Page 11 Monday, April 17, 2006 11:26 AM

PERIODIC MAINTENANCE AND MINOR REPAIR
6-12
6
EAU41230
Cleaning the spark arrester The spark arrester should be cleaned
at the intervals specified in the periodic
maintenance and lubrication chart.
WARNING
EWA10980


Always let the exhaust system
cool prior to touching exhaust
components.


Do not start the engine whencleaning the exhaust system.
NOTE:Make sure to select a well-ventilated
area free of combustible materials toclean the spark arrester.
1. Remove the tailpipe by removing
the bolt, and then pulling it out of
the muffler.2. Tap the tailpipe lightly, and then
use a wire brush to remove any
carbon deposits from the spark ar-
rester portion of the tailpipe and in-
side of the tailpipe housing.3. Insert the tailpipe into the muffler,
and then install and tighten the
bolt.
NOTE:Make sure to align the bolt hole wheninserting the tailpipe.
1. Bolt
1. Tailpipe
2. Spark arrester
U3P281E0.book Page 12 Monday, April 17, 2006 11:26 AM

PERIODIC MAINTENANCE AND MINOR REPAIR
6-13
6
EAU39930
Adjusting the carburetor The carburetor is an important part of
the engine and requires very sophisti-
cated adjustment. Therefore, most car-
buretor adjustments should be left to a
Yamaha dealer, who has the neces-
sary professional knowledge and expe-
rience. The adjustment described in the
following section, however, may be ser-
viced by the owner as part of routine
maintenance.CAUTION:
ECA10550
The carburetor has been set and ex-
tensively tested at the Yamaha fac-
tory. Changing these settings
without sufficient technical knowl-
edge may result in poor perfor-mance of or damage to the engine.
EAU21360
Adjusting the engine idling
speed The engine idling speed must be
checked and, if necessary, adjusted as
follows at the intervals specified in the
periodic maintenance and lubrication
chart.NOTE:
A diagnostic tachometer is needed tomake this adjustment.
1. Attach the tachometer to the spark
plug lead.
2. Start the engine and warm it up for
several minutes at 1000–2000
r/min while occasionally revving it
to 4000–5000 r/min.NOTE:The engine is warm when it quickly re-sponds to the throttle.
3. Check the engine idling speed
and, if necessary, adjust it to spec-
ification by turning the throttle stop
screw. To increase the engine
idling speed, turn the screw in di-rection (a). To decrease the en-
gine idling speed, turn the screw in
direction (b).
NOTE:
If the specified idling speed cannot be
obtained as described above, have aYamaha dealer make the adjustment.1. Throttle stop screw
Engine idling speed:
1400–1600 r/min
U3P281E0.book Page 13 Monday, April 17, 2006 11:26 AM

PERIODIC MAINTENANCE AND MINOR REPAIR
6-14
6
EAU21370
Adjusting 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, 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).
3. Tighten the locknut.
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.
1. Throttle cable free play adjusting nut
2. Locknut
3. Throttle cable free playU3P281E0.book Page 14 Monday, April 17, 2006 11:26 AM

PERIODIC MAINTENANCE AND MINOR REPAIR
6-19
6 4. If the drive chain slack is incorrect,
adjust it as follows.
EAU40110
To adjust the drive chain slack
1. Loosen the brake pedal free play
adjusting nut, axle nut, and locknut
at each end of the swingarm.2. To tighten the drive chain, turn the
adjusting nut at each end of the
swingarm in direction (a). To loos-
en the drive chain, turn the adjust-
ing nut at each end of the
swingarm in direction (b), and then
push the rear wheel forward.
NOTE:Using the alignment marks on each
side of the swingarm, make sure that
both adjusting nuts are in the same po-sition for proper wheel alignment.
CAUTION:
ECA10570
Improper drive chain slack will over-
load the engine as well as other vital
parts of the motorcycle and can lead
to chain slippage or breakage. To
prevent this from occurring, keep
the drive chain slack within thespecified limits.
3. Tighten both locknuts and the axle
nut to the specified torques.
1. Drive chain slack
1. Brake pedal free play adjusting nut
2. Locknut
3. Drive chain slack adjusting nut
1. Axle nut
2. Drive chain slack adjusting nut
3. Locknut
4. Alignment marks
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PERIODIC MAINTENANCE AND MINOR REPAIR
6-21
6
EAU23090
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
EWA10710
Damage to the outer housing of ca-
bles may result in internal rusting
and cause interference with cable
movement. Replace damaged ca-
bles as soon as possible to preventunsafe conditions.
EAU23111
Checking and lubricating the
throttle grip and cable The operation of the throttle grip should
be checked before each ride. In addi-
tion, the cable should be lubricated at
the intervals specified in the periodic
maintenance chart.
EAU23131
Checking and lubricating the
brake and shift pedals The operation of the brake and shift
pedals should be checked before each
ride, and the pedal pivots should be lu-
bricated if necessary.
Recommended lubricant:
Yamaha Chain and Cable Lube or
engine oil SAE 10W-30 (API SE)
Recommended lubricant:
Lithium-soap-based grease (all-pur-
pose grease)
U3P281E0.book Page 21 Monday, April 17, 2006 11:26 AM

PERIODIC MAINTENANCE AND MINOR REPAIR
6-23
6
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 thatthere 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 thatthere 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.
U3P281E0.book Page 23 Monday, April 17, 2006 11:26 AM