2003 YAMAHA TTR90 heater

2 - 18
SPEC

CABLE ROUTING DIAGRAM
1
Clamp
2
Engine stop switch lead
3
Main switch lead
4
Start switch lead
5
Brake cable
6
Throttle cable
7
Fuel tank breather hose
8
Ignition coil
9
Wire harness
0
Starter relay
A
Starter motor lead
B
Crankcase breather hose
C
Starter motor lead
D
Neutral switch lead
E
CDI magneto lead
F
CDI unit
G
Fuel overflow hose
HSpark plug lead
IFuel hose
JCarburetor heater lead
KCarburetor breather hose
LCarburetor heater couplerMCDI magneto coupler
NCDI unit coupler
OCDI unit connector
PCDI unit lead
QThermo switch lead
RThermo switch
SStarting circuit cut-off relay
TStarting circuit cut-off relay lead
URectifier/regulator lead
VRectifier/regulator
WStarter relay lead
A AA
C C
D
B
B B
BF FF
EE
D
A - AB - BE - E
C
F - FG - GD
KK
QRÔ
8
E
H
˜ 2 3 4
6
5
4
3
2
1
J
I
H
G
F
E
D
CBA 0 Ï 9 8 Î K 7
S
W U
V
A
0
Í T 99
QP
PT
9 
Ò
ˆ Ø
Ç ı
Å
Ó
Œ
Â
E
GGA
P
O
NML 9
È
9
Ì
Ê
Ë
25 mm (1.0 in)
∏
‰

2 - 19
SPECCABLE ROUTING DIAGRAM
ÅPass the start switch lead, main
switch lead, engine stop switch
lead and throttle cable through
the cable guide.
ıPass the fuel tank breather hose
through the hose guide.
ÇPass the carburetor breather
hose through the hose guide.
ÎFasten the carburetor heater lead,
main switch lead, engine stop
switch lead and start switch lead.‰After fastening the CDI mag-
neto lead, cut off any excess
from the plastic locking tie end.
ÏFasten the battery leads to the
bracket with the plastic locking
tie. For fastening, pass the plas-
tic locking tie through the hole in
the bracket.
ÌAfter fastening the starter motor
lead, cut off any excess from the
plastic locking tie end.ÓAfter fastening the CDI mag-
neto lead, cut off any excess
from the plastic locking tie end.
ÈPosition the start switch coupler
and engine stop switch coupler
between the carburetor breather
hose and thermo switch.
ÔMake sure that the CDI unit lead
does not contact the thermo
switch bracket.
A AA
C C
D
B
B B
BF FF
EE
D
A - AB - BE - E
C
F - FG - GD
KK
QRÔ
8
E
H
˜ 2 3 4
6
5
4
3
2
1
J
I
H
G
F
E
D
CBA 0 Ï 9 8 Î K 7
S
W U
V
A
0
Í T 99
QP
PT
9 
Ò
ˆ Ø
Ç ı
Å
Ó
Œ
Â
E
GGA
P
O
NML 9
È
9
Ì
Ê
Ë
25 mm (1.0 in)
∏
‰

2 - 20
SPEC
Fasten the starter cable, thermo
switch lead, CDI unit lead, main
switch lead, start switch lead
and engine stop switch lead.
ÒFasten the wire harness, CDI
unit leads, thermo switch lead
and CDI magneto lead.
˜Pass the carburetor heater lead
between the carburetor breather
hose and air intake duct.ˆPosition the main switch cou-
pler between the carburetor
breather hose and air intake
duct.
ØFasten the start switch lead,
main switch lead and engine
stop switch lead at the tape with
the plastic locking tie.
∏Fasten the battery leads.ŒFasten the wire harness and
starting circuit cut-off relay lead
at the tape for the wire harness
with the plastic locking tie.
ÂFasten the rectifier/regulator
lead and starter relay leads. For
fastening, pass the plastic lock-
ing tie through the hole in the
battery box.
A AA
C C
D
B
B B
BF FF
EE
D
A - AB - BE - E
C
F - FG - GD
KK
QRÔ
8
E
H
˜ 2 3 4
6
5
4
3
2
1
J
I
H
G
F
E
D
CBA 0 Ï 9 8 Î K 7
S
W U
V
A
0
Í T 99
QP
PT
9 
Ò
ˆ Ø
Ç ı
Å
Ó
Œ
Â
E
GGA
P
O
NML 9
È
9
Ì
Ê
Ë
25 mm (1.0 in)
∏
‰
CABLE ROUTING DIAGRAM

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 - 3
ENG

CARBURETOR
Extent of removal Order Part name Q’ty Remarks
A
Float pin 1
B
Float 1
C
Needle valve 1
D
Main jet 1
E
Pilot jet 1
F
Needle jet 1
G
Throttle stop screw assembly 1
H
Pilot air screw assembly 1
I
Carburetor heater
1
1

6 - 1
–+ELEC

12
3
456
7
0
98

A
B
F
EC
D

ELECTRICAL COMPONENTS AND WIRING DIAGRAM
EC600000
ELECTRICAL
EC610000
ELECTRICAL COMPONENTS AND WIRING DIAGRAM
EC611000
ELECTRICAL COMPONENTS
1
Main switch
2
“ENGINE STOP”
switch
3
Thermo switch
4
Ignition coil
5
CDI unit
6
Battery
7
Rectifier/regulator
8
Neutral switch
9
CDI magneto
0
Carburetor heater
A
Starter relay
B
Fuse
C
Start switch
D
Spark plug
E
Starter motor
F
Starting circuit cut-off
relay
COLOR CODE
B ...................... Black
Br .................... Brown
G ..................... Green
O ..................... Orange
R ..................... Red
Sb .................... Sky blue
W ..................... White
Y ...................... Yellow
EC612000
WIRING DIAGRAM
G/WB/RW/LW/RBr G
RW
B/WBr BRB/WBBrR
B/WB BB
BR/WBr B
GG/W
B/W
B/W
BrB/RWWOO
B
BW/LY/RR
W
B
B
R
W/RY/R
OFF RUNB
Y/R
Y
Y
OBO BY/RYB B
Sb
W W
Sb
ON OFF
OFFON
Y
BB
Y/R
Br
Br
B
B
R
RR
R
B
R/WR/W
R/WR/W
R/W
Sb
Sb
RB
R/WB R
Y/RRB W
B/WB
R/W
R/W
R/W
Sb
9
8
1 B5
4
D
2 3
=A
E 6
C
F 7

B/R ................... Black/Red
B/W .................. Black/White
G/W.................. Green/White
R/W .................. Red/White
W/L .................. White/Blue
W/R .................. White/Red
Y/R ................... Yellow/Red

–+ELEC
6 - 16
CARBURETOR HEATING SYSTEM
CARBURETOR HEATING SYSTEM
INSPECTION STEPS
Use the following steps for checking the possibility of the malfunctioning carburetor heating system.
NOTE:
Remove the following parts before inspection.
1) Seat
2) Fuel tank
Use 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. Lighting 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 - 18
–+ELECCARBURETOR HEATING SYSTEM
WARNING
Handle the thermo switch with special
care.
Never subject the thermo switch to
strong shocks. If the thermo switch is
dropped, replace it.
Check the thermo switch operation.
CARBURETOR HEATER INSPECTION
1. Inspect:
Carburetor 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 Ω at
20 ˚C (68 ˚F)Ω × 1
CDI MAGNETO INSPECTION
1. Inspect:
Lighting coil resistance
Out of specification → Replace.
Tester (+) lead → Yellow lead 1
Tester (–) lead → Black lead 2
Lighting coil
resistanceTester selector
position
0.52 ~ 0.78 Ω at
20 ˚C (68 ˚F)Ω × 1
WSb
YB
1
2