2002 YAMAHA TTR90 heater

4 - 1
ENG
ENGINE
CARBURETOR
Extent of removal:1 Carburetor removal
Extent of removal Order Part name Q’ty Remarks
CARBURETOR REMOVAL
Preparation for removal Fuel tank
1 Clamp (air filter joint) 1 Loosen the screw (air filter joint).
2 Carburetor heater lead 1
3 Air vent hose 1
4 Fuel hose 1
5 Bolt 2
6 Carburetor assembly 1
7 O-ring 1
8 Spacer 1
9 Carburetor top 1
10 Starter plunger assembly 1
1
CARBURETOR
4

4 - 3
ENGCARBURETOR
Extent of removal Order Part name Q’ty Remarks
AFloat pin 1
BFloat 1
CNeedle valve 1
DMain jet 1
EPilot jet 1
FNeedle jet 1
GThrottle stop screw assembly 1
HPilot air screw assembly 1
ICarburetor heater
1
1

6 - 1
–+ELECELECTRICAL COMPONENTS AND WIRING DIAGRAM
EC600000
ELECTRICAL
EC610000
ELECTRICAL COMPONENTS AND WIRING DIAGRAM
EC611000
ELECTRICAL COMPONENTS
1CDI magneto
2CDI unit
3Ignition coil
4Spark plug
5“ENGINE STOP” switch
6Thermo switch
7Carburetor heater
8Rectifier/regulatorCOLOR CODE
B...................... Black
Br .................... Brown
G ..................... Green
O ..................... Orange
R ..................... Red
W..................... White
EC612000
WIRING DIAGRAM
G/WB/RW/LW/RBr G
RW
WB
Y/R
O
BO
B
B
BY/RY
WY/RB
W
Y
B
GG/W
B/W
B/W
BrB/RWWWY
OO
BBW/LY/RR
W
B
B
B
W/R
Y/R
OFF
RUN
B
Y/R
B
B
Y
Y
1
23
4
5 6
7 8
B/R ................... Black/Red
B/W .................. Black/White
G/W.................. Green/White
W/L .................. White/Blue
W/R .................. White/Red
6

–+ELEC
6 - 6
CARBURETOR HEATING SYSTEM
CARBURETOR HEATING SYSTEM
INSPECTION STEPS
Use the following steps for checking the possibility of the malfunctioning carburetor heating system.
NOTE:
lRemove the following parts before inspection.
1) Seat
2) Fuel tank
lUse the following special tools in this inspection.
Check entire carburetor
heating system for connec-
tion.Repair or replace.
Check thermo switch. Replace.
Check carburetor heater. Replace.
Check CDI magneto. Source coil Replace.
Replace rectifier/regulator.
Pocket tester:
YU-3112-C/90890-03112
OK
OK
OK
No good
No good
No good
No good
OK

6 - 8
–+ELECCARBURETOR HEATING SYSTEM
The thermo switch circuit is open.
õThe thermo switch circuit is closed.
Test step Water temperature Continuity
1Less than 23 ± 3 ˚C
(73.4 ± 5.4 ˚F)YES
2More than 23 ± 3 ˚C
(73.4 ± 5.4 ˚F)NO
3More than 12 ± 4 ˚C
(53.6 ± 7.2 ˚F)NO
4Less than 12 ± 4 ˚C
(53.6 ± 7.2 ˚F)YES
Test steps 1 & 2: Heating phase
Test steps 3 & 4: Cooling phase
WARNING
lHandle the thermo switch with special
care.
lNever subject the thermo switch to
strong shocks. If the thermo switch is
dropped, replace it.
lCheck the thermo switch operation.
CARBURETOR HEATER INSPECTION
1. Inspect:
lCarburetor heater resistance
Out of specification ® Replace.
Tester (+) probe ®
Carburetor heater terminal 1
Tester (–) probe ®
Carburetor heater body 2
Carburetor
heater resistanceTester selector
position
6 ~ 10 W at
20˚C (68 ˚F)W ´ 1