2002 YAMAHA TTR90 transmission

6. When going for riding, be sure to be with
your family.
Never go alone.
7. Before riding the machine, ask your par-
ents to check the machine very carefully.
8. Don’t touch the areas shown, or you’ll get
burnt in the hand.
9. Don’t touch rotating or moving parts.
10. Before starting the engine, be sure to shift
the transmission into neutral.

CHAPTER 4
ENGINE
CARBURETOR ......................................... 4-1
CYLINDER HEAD ..................................... 4-8
CAMSHAFT AND ROCKER ARMS ....... 4-13
VALVES AND VALVE SPRINGS ........... 4-16
CYLINDER AND PISTON ....................... 4-21
CLUTCH .................................................. 4-27
KICK AXLE ............................................. 4-33
SHIFT SHAFT ......................................... 4-34
OIL PUMP ............................................... 4-36
CDI MAGNETO ....................................... 4-39
CRANKCASE AND CRANKSHAFT ....... 4-41
SHIFT FORK, SHIFT CAM AND
TRANSMISSION ..................................... 4-44
CHAPTER 5
CHASSIS
FRONT WHEEL AND REAR WHEEL ...... 5-1
FRONT FORK ........................................... 5-6
HANDLEBAR ............................................ 5-9
STEERING .............................................. 5-10
SWINGARM ............................................ 5-11
CHAPTER 6
ELECTRICAL
ELECTRICAL COMPONENTS AND
WIRING DIAGRAM ................................... 6-1
IGNITION SYSTEM ................................... 6-2
CARBURETOR HEATING SYSTEM ........ 6-6
MAINTENANCE RECORD ....................... 6-9

GEN
INFODESCRIPTION
FAHRZEUGBESCHREIBUNG
ALLGEMEINE ANGABEN
FAHRZEUGBESCHREIBUNG
1Motorstoppschalter
2Handbremshebel
3Gasdrehgriff
4Motoröl-Einfüllschraubverschluß/Tauchstab
5Kickstarter
6Kraftstofftank
7Luftfilter
8Fußbremshebel
9Kraftstoffhahn
0Chokehebel
AAntriebskette
BSchalthebel
CTeleskopgabel
HINWEIS:
lLeichte Modell-Abweichungen möglich.
lÄnderungen an Design und technischen Da-
ten jederzeit vorbehalten.
RENSEIGNEMENTS
GENERAUX
DESCRIPTION
1Coupe-circuit du moteur
2Levier de frein avant
3Poignée d’accélérateur
4Bouchon d’orifice de remplissage et jauge d’huile
5Kick
6Réservoir de carburant
7Filtre à air
8Pédale de frein arrière
9Robinet à essence
0Levier de starter
AChaîne de transmission
BPédale de sélection
CFourche avant
N.B.:
lVotre machine diffère peut-être partiellement de
celles montrées sur ces photos.
lLa conception et les caractéristiques peuvent
êtres changées sans préavis.
1 - 1
1

1 - 9
GEN
INFO
CONTROL FUNCTIONS
EC150000
CONTROL FUNCTIONS
“ENGINE STOP” SWITCH
Make sure that the engine stop switch 1 is
positioned to “ ”. The engine stop switch has
been equipped to ensure safety in an emer-
gency such when the machine is up set or
trouble takes place in the throttle system. The
engine will not start or run when the engine
stop switch is turned to “ ”.
SHIFT PEDAL
The gear ratios of the constant-mesh 3 speed
transmission are ideally spaced. The gears
can be shifted by using the shift pedal 1 on
the left side of the engine.
WARNING
When starting out on the machine, shift the
transmission into 1st after pulling in the
front brake lever and closing the throttle
grip.
KICK STARTER
WARNING
Before starting the engine, be sure to shift
the transmission into neutral.
Rotate the kick starter 1 away from the
engine. Push the starter down lightly with your
foot until the gears engage, then kick smoothly
and forcefully to start the engine.
EC155001
THROTTLE GRIP
The throttle grip 1 is located on the right han-
dlebar; it accelerates or decelerates the
engine. For acceleration, turn the grip toward
you; for deceleration, turn it away from you.

1 - 12
GEN
INFO
STARTING AND OPERATION
STARTING AND OPERATION
CAUTION:
Prior to operating the machine, perform
steps listed in pre-operation check list.
WARNING
Never start your engine or let it run for any
length of time in a closed area. The exhaust
fumes are poisonous and can cause loss of
consciousness and death within a short
time. Always operate your machine in an
area with adequate ventilation.
STARTING A COLD ENGINE
WARNING
Before starting the engine, be sure to shift
the transmission into neutral.
1. Turn the fuel cock to “ON”.
2. Operate the starter (choke) and com-
pletely close the throttle grip.
3. Slide the “ENGINE STOP” switch to the
“”.
4. Kick the kick starter with full strength to
start the engine.
5. After the engine starts, warm up for one
or two minutes. Make sure the stater
(choke) is returned to the original position
before riding.
STARTING A WARM ENGINE
To start a warm engine, refer to the “Starting a
cold engine” section. The starter (choke)
should not be used. The throttle should be
opened slightly.
CAUTION:
See “Engine break-in Section” prior to
operating engine for the first time.WARMING UP
To get maximum engine life, always “warm-up”
the engine before starting off. Never acceler-
ate hard with a cold engine! To see whether or
not the engine is warm, see if it responds to
throttle normally with the stater (choke) turned
off.
WARNING
Before starting off, be sure to turn up or
remove the side stand.
Failure to retract the side stand completely
can result in a serious accident when you
try to turn a corner.
ENGINE BREAK-IN
Brake-in is important to better fit the moving
and sliding parts as well as the installed parts.
It is also important to accustom the rider to the
machine better.
Avoid full-throttle run on a new machine for the
first 5 hours.
After the trial run, check for loose parts, oil
leakage and other problems.
Make full inspection and adjustment especially
of slack cables and drive chain and loose
spokes.
CAUTION:
After the break-in period, check every fit-
ting and fastener for looseness.
If any loose is found, retighten it securely.

SPEC
2 - 2
Oil capacity:
Engine oil
Periodic oil change 0.8 L (0.70 Imp qt, 0.85 US qt)
Total amount 1.0 L (0.88 Imp qt, 1.06 US qt)
Air filter: Wet type element
Fuel:
Type Unleaded gasoline only (USA, AUS and NZ)
Regular unleaded gasoline only (CDN, Europe)
Regular gasoline (ZA)
Tank capacity 4.2 L (0.92 lmp gal, 1.11 US gal)
Reserve amount 0.5 L (0.11 Imp gal, 0.13 US gal)
Carburetor:
Type VM16SH
Manufacturer MIKUNI
Spark plug:
Type CR6HSA/U20FSR-U
Manufacturer NGK/DENSO
Gap 0.6 ~ 0.7 mm (0.02 ~ 0.03 in)
Clutch type: Wet, multiple-disc and centrifugal automatic
Transmission:
Primary reduction system Spur gear
Primary reduction ratio 67/18 (3.722)
Secondary reduction system Chain drive
Secondary reduction ratio 35/14 (2.500)
Transmission type Constant mesh, 3-speed
Operation Left foot operation
Gear ratio: 1st 37/13 (2.846)
2nd 33/19 (1.736)
3rd 28/23 (1.217)
Chassis:
Frame type Double cradle
Caster angle 24.83˚
Trail 56.0 mm (2.2 in)
Tire:
Type With tube
Size (front) 2.50-14 4PR
Size (rear) 3.00-12 4PR
Manufacturer (front and rear) CHENG SHIN
Type (front and rear) KNOBBY
Tire pressure (front and rear) 100 kPa (1.00 kg/cm
2, 14.5 psi)
GENERAL SPECIFICATIONS
2

2 - 4
CARACTERISTIQUES D’ENTRETIENSPEC
CARACTERISTIQUES D’ENTRETIEN
MOTEUR
Désignation Standard Limite
Culasse:
Limite de déformation ---- 0,03 mm
(0,0012 in)
Cylindre:
Alésage 47,000 à 47,005 mm
(1,8504 à 1,8506 in)47,05 mm
(1,8524 in)
Limite d’ovalisation ---- 0,05 mm
(0,0020 in)
Arbre à cames:
Méthode d’entraînement Transmission par chaîne
(côté gauche)----
Dimensions de came
Admission “A” 25,428 à 25,528 mm
(1,0011 à 1,0050 in)25,328 mm
(0,9972 in)
“B” 21,034 à 21,134 mm
(0,8281 à 0,8320 in)20,934 mm
(0,8242 in)
Echappement “A” 25,286 à 25,386 mm
(0,9955 à 0,9994 in)25,186 mm
(0,9916 in)
“B” 21,047 à 21,147 mm
(0,8286 à 0,8326 in)20,947 mm
(0,8247 in)
Limite de voile d’arbre à cames ---- 0,03 mm
(0,0012 in)

2 - 10
CARACTERISTIQUES D’ENTRETIENSPEC
Pièce à serrerDiamètre de
filetQtéCouple de serrage
Nm m•kg ft•lb
Ecrou de culasse M8 ´ 1,25 4 22 2,2 16
Boulon de culasse M6 ´ 1,0 2 10 1,0 7,2
Bougie M10 ´ 1,0 1 13 1,3 9,4
Boulon de cache de pignon d’arbre à came M6 ´ 1,0 2 7 0,7 5,1
Cache de poussoir M45 ´ 1,5 2 18 1,8 13
Boulon prisonnier de tuyau d’échappement M6 ´ 1,0 2 7 0,7 5,1
Ecrou de rotor M12 ´ 1,25 1 48 4,8 35
Patin de chaîne de distribution (arrière) M6 ´ 1,0 2 10 1,0 7,2
Contre-écrou de vis de réglage du jeu de soupape M5 ´ 0,5 2 7 0,7 5,1
Pignon d’arbre à cames M8 ´ 1,25 1 20 2,0 14
Retenue de roulement d’arbre à cames M6 ´ 1,0 1 10 1,0 7,2
Boulon capuchon du tendeur de chaîne de distribution M8 ´ 1,25 1 8 0,8 5,8
Tendeur de chaîne de distribution M6 ´ 1,0 2 10 1,0 7,2
Pompe à huile M6 ´ 1,0 2 7 0,7 5,1
Bouchon de vidange M12 ´ 1,5 1 20 2,0 14
Raccord de carburateur (côté culasse) M6 ´ 1,0 2 7 0,7 5,1
Raccord de carburateur (côté carburateur) M6 ´ 1,0 2 7 0,7 5,1
Boîtier de filtre à air M6 ´ 1,0 2 7 0,7 5,1
Tuyau d’échappement M6 ´ 1,0 2 7 0,7 5,1
Protection de tuyau d’échappement M6 ´ 1,0 7 7 0,7 5,1
Silencieux M8 ´ 1,25 1 24 2,4 17
Protection de silencieux M5 ´ 0,8 2 4 0,4 2,9
Carter M6 ´ 1,0 9 10 1,0 7,2
Demi-carter (gauche) M6 ´ 1,0 8 7 0,7 5,1
Cache de pignon menant M6 ´ 1,0 2 7 0,7 5,1
Demi-carter (droit) M6 ´ 1,0 9 7 0,7 5,1
Bouchon de distribution M14 ´ 1,5 1 7 0,7 5,1
Cache d’extrémité de vilebrequin M32 ´ 1,5 1 7 0,7 5,1
Boulon prisonnier de culasse M8 ´ 1,25 4 13 1,3 9,4
Pédale de kick M6 ´ 1,0 1 10 1,0 7,2
Pignon de transmission primaire M12 ´ 1,0 1 50 5,0 36
Plateau de pression M5 ´ 0,8 4 6 0,6 4,3
Noix d’embrayage M14 ´ 1,0 1 70 7,0 50
Retenue de roulement d’arbre primaire M6 ´ 1,0 1 10 1,0 7,2
Pédale de sélection M6 ´ 1,0 1 8 0,8 5,8
Contre-écrou de vis de réglage d’embrayage M6 ´ 1,0 1 8 0,8 5,8
Bobine d’excitation M6 ´ 1,0 2 10 1,0 7,2
Ensemble stator M6 ´ 1,0 3 10 1,0 7,2