2000 YAMAHA TTR90 engine

5 - 9
CHASHANDLEBAR
EC5B000
HANDLEBAR
Extent of removal:1 Handlebar removal
Extent of removal Order Part name Q’ty Remarks
HANDLEBAR REMOVAL
1 “ENGINE STOP” switch 1
2 Brake lever cable 1 Disconnect at the lever side.
3 Brake lever 1
4 Grip cap (lower) 1
5 Grip cap (upper) 1
6 Throttle cable 1 Disconnect at the throttle side.
7 Grip (right) 1
8 Tube guide 1
9 Grip (left) 1
10 Handlebar holder (upper) 2
11 Handlebar 1
12 Handlebar holder (lower) 2
1

5 - 10
CHASSTEERING
EC560000
STEERING
LS
LS
T R..TIGHTENING STEPS:
•Tighten ring nut.
38 Nm (3.8 m • kg, 27 ft • Ib)
•Loosen it completly
•Retighten it.
1 Nm (0.1 m • kg, 0.7 ft • Ib)
T R..40 Nm (4.0 m • kg, 29 ft • Ib)
5 9681076 43
21
Extent of removal:1 Under bracket removal2 Bearing removal
Extent of removal Order Part name Q’ty Remarks
STEERING REMOVAL
Preparation for removal Hold the machine by placing the
suitable stand under the engine.
Front fork Refer to “FRONT FORK” section.
1 Steering stem bolt 1
2 Handle crown 1
3 Ring nut 1 Use special tool.
Refer to “STEERING HEAD INSPEC-
TION AND ADJUSTMENT” section in
the CHAPTER 3.
4 Ball race cover 1
5 Under bracket 1
6 Bearing inner race 2
7 Upper bearing ball 19
8 Lower bearing ball 16
9 Dust seal 1
10 Bearing outer race 2
WARNING
Support the machine securely so there is nodanger of it falling over.
2
1

5 - 11
CHASSWINGARM
EC570000
SWINGARM
Extent of removal:1 Swingarm removal2 Rear shock absorber removal
Extent of removal Order Part name Q’ty Remarks
SWINGARM REMOVAL
Preparation for removal Hold the machine by placing the
suitable stand under the engine.
Rear wheel Refer to “REAR WHEEL AND REAR
BRAKE” section.
Rear fender
Drive chain
1 Cotter pin 2
2 Pin 2
3 Rear shock absorber 1
4 Pivot shaft 1 Hold the swingarm.
5 Swing arm 1
6 Chain guard 1
7 Chain case (upper) 1
8 Chain case (lower) 1
WARNING
Support the machine securely so there is nodanger of it falling over.
1
2

6 - 1
–+ELEC

ELECTRICAL COMPONENTS AND WIRING DIAGRAM
EC600000
ELECTRICAL
EC610000
ELECTRICAL COMPONENTS AND WIRING DIAGRAM
EC611000
ELECTRICAL COMPONENTS
1
CDI magneto
2
CDI unit
3
Ignition coil
4
Spark plug
5
“ENGINE STOP” switch
6
Thermo switch
7
Carburetor heater
8
Rectifier/regulator
COLOR 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 - 2
IGNITION SYSTEM
EC620000
IGNITION SYSTEM
EC621001
INSPECTION STEPS
Use the following steps for checking the possibility of the malfunctioning engine being attributable to
ignition system failure and for checking the spark plug which will not spark.
NOTE:

l
Remove the following parts before inspection.
1) Seat
2) Fuel tank
l
Use the following special tools in this inspection.
Spark gap testClean or replace
spark plug.
Check entire ignition
system for connection.Repair or replace.
Check “ENGINE STOP”
switch.Replace.
Check ignition coil. Primary coil Replace.
Secondary coilReplace.
Check CDI magneto. Pickup coil Replace.
Source coil Replace.
Replace CDI unit.
Dynamic spark tester:
YM-34487
Ignition checker:
90890-06754
Pocket tester:
YU-03112/90890-03112
No Spark
OK
OK
OK
OK
Spark
No good
No good
No good
No good
No good
No good

6 - 3
–+ELEC

IGNITION SYSTEM
EC622001
SPARK GAP TEST
1. Disconnect the spark plug cap from spark
plug.
2. Connect the dynamic spark tester
1
(ignition checker
2
) as shown.
l
Spark plug cap
3

l
Spark plug
4


For USA and CDN
õ
Except for USA and CDN
3. Kick the kick starter.
4. Check the ignition spark gap.
5. Start engine, and increase spark gap until
misfire occurs. (for USA and CDN only)
Minimum spark gap:
6.0 mm (0.24 in)

õ

EC624000
COUPLERS AND LEADS CONNECTION
INSPECTION
1. Check:
l
Couplers and leads connection
Rust/dust/looseness/short-circuit
®

Repair or replace.
EC625001
“ENGINE STOP” SWITCH INSPECTION
1. Inspect:
l
“ENGINE STOP” switch continuity
No continuity while being pushed “ ”
®
Replace.
Continuity while being pushed “ ”
®
Replace.
Tester (+) lead
®
Black/White lead
1

Tester (–) lead
®
Black lead
2

B/W
1
B
2
Tester selec-
tor position
W

´
1