2000 YAMAHA TTR90 heating

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

–+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-03112/90890-03112
OK
OK
OK
No good
No good
No good
No good
OK

6 - 7
–+ELECCARBURETOR HEATING SYSTEM
EC624000
COUPLERS AND LEADS CONNECTION
INSPECTION
1. Check:
lCouplers and leads connection
Rust/dust/looseness/short-circuit ®
Repair or replace.
CDI MAGNETO INSPECTION
1. Inspect:
lSource coil resistance
Refer to “IGNITION SYSTEM” section.
THERMO SWITCH INSPECTION
1. Inspect:
lThermo switch operation
Faulty operation ® Replace.
Inspection steps:
lRemove the thermo switch.
lConnect the pocket tester to the thermo
switch coupler as shown.
Tester (+) lead ® black 1
Tester (–) lead ® black 2
lImmerse the thermo switch in a container
filled with water 3.
lPlace a thermometer 4 in the water.
lSlowly heat the water, and then let it cool to
the specified temperature as indicated in
the table.
lCheck the thermo switch for continuity at
the temperatures indicated in the table.

6 - 8
–+ELEC

CARBURETOR HEATING SYSTEM

The thermo switch circuit is open.
õ
The thermo switch circuit is closed.
Test step Water temperatureContinu-
ity
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
l
Check the thermo switch operation.
WARNING
lHandle the thermo switch with special
care.
lNever subject the thermo switch to
strong shocks. If the thermo switch is
dropped, replace it.
CARBURETOR HEATER INSPECTION
1. Inspect:

l
Carburetor heater resistance
Out of specification
®
Replace.
Tester (+) probe
®

carburetor heater terminal
1
Tester (–) probe
®
carburetor heater body
2
Carburetor heater resistance:
6 ~ 10
W
at 20 ˚C (68 ˚F)