fuel YAMAHA TTR90 2005 Owner's Manual

4 - 7
ENGCARBURETOR
1. Measure:
Fuel level a
Use a fuel level gauge 1.
Out of specification → Adjust.
Fuel level gauge:
YM-1312-A/90890-01312
Fuel level:
2 ~ 3 mm (0.08 ~ 0.12 in) below
the float chamber line

4 - 8
ENGCYLINDER HEAD
CYLINDER HEAD
Extent of removal:1 Cylinder head removal
Extent of removal Order Part name Q’ty Remarks
CYLINDER HEAD REMOVAL
Preparation for removal Seat, fuel tank and rear fender
Exhaust pipe
Carburetor Refer to “CARBURETOR” section.
Air filter case and starter lever
1 Plug cap/spark plug 1/1
2 Crankshaft end cover/O-ring 1/1
3 Timing plug/O-ring 1/1
4 Camshaft sprocket cover/O-ring 1/1
5 Tappet cover (intake)/O-ring 1/1
6 Tappet cover (exhaust)/O-ring 1/1
7 Camshaft sprocket bolt/washer 1/1
Refer to “REMOVAL POINTS”. 8 Timing chain tensioner 1
9 Gasket 1
1

4 - 39
ENG
CDI MAGNETO (TT-R90)
Extent of removal:1 Pickup coil/stator assembly removal2 Rotor removal
Extent of removal Order Part name Q’ty Remarks
CDI MAGNETO AND STATOR
REMOVAL
Preparation for removal Fuel tank
Crankcase cover (left) Refer to “CLUTCH” section.
1 CDI magneto coupler 1
2 Pickup coil/stator assembly 1
3 Rotor nut 1
Use special tool.
Refer to “REMOVAL POINTS”. 4 Rotor 1
5 Woodruff key 1
1
2
CDI MAGNETO (TT-R90)

4 - 41
ENGCDI MAGNETO AND STARTER CLUTCH (TT-R90E)
CDI MAGNETO AND STARTER CLUTCH (TT-R90E)
Extent of removal:1 Pickup coil/stator removal2 Rotor removal
3 Starter clutch/wheel gear removal
Extent of removal Order Part name Q’ty Remarks
CDI MAGNETO AND STATOR
REMOVAL
Preparation for removal Fuel tank
Crankcase cover (left) Refer to “CLUTCH” section.
1 CDI magneto coupler 1
2 Pickup coil/stator assembly 1
3 Rotor nut 1
Use special tool.
Refer to “REMOVAL POINTS”. 4 Rotor 1
5 Woodruff key 1
6 Shaft 1
7 Idler gear 1
8 Starter clutch/wheel gear 1/1
1
2
3

4 - 45
ENGCRANKCASE AND CRANKSHAFT
CRANKCASE AND CRANKSHAFT
Extent of removal Order Part name Q’ty Remarks
CRANKCASE SEPARATION
AND CRANKSHAFT REMOVAL
Preparation for removal Seat, fuel tank and rear fender
Exhaust pipe
Air filter case
Carburetor Refer to “CARBURETOR” section.
Drain the engine oil Refer to “ENGINE OIL REPLACEMENT”
section in the CHAPTER 3.
Engine guard and drive sprocket
Engine assembly From the chassis.
Cylinder head Refer to “CYLINDER HEAD” section.
Cylinder and piston Refer to “CYLINDER AND PISTON” sec-
tion.
Clutch housing and clutch carrier Refer to “CLUTCH” section.
Kick axle assembly Refer to “KICK AXLE” section.

–+ELEC
6 - 3
IGNITION SYSTEM
EC620000
IGNITION SYSTEM
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:
Remove the following parts before inspection.
1) Seat
2) Fuel tank
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 main switch.
(TT-R90E only)Replace.
Check “ENGINE STOP”
switch.Replace.
Check ignition coil. Primary coil Replace.
Secondary coil Replace.
Check CDI magneto. Pickup coil Replace.
Source coil Replace.
Replace CDI unit.
Dynamic spark tester:
YM-34487
Ignition checker:
90890-06754Pocket tester:
YU-3112-C/90890-03112
No Spark
OK
OK
OK
OK
Spark
No good
No good
No good
No good
No good
No good
OK
No good

–+ELEC
6 - 8 INSPECTION STEPS
If the starter motor will not operate, use the following inspection steps.
*1 marked: Refer to “FUSE INSPECTION” section in the CHAPTER 3.
*2 marked: Refer to “BATTERY INSPECTION AND CHARGING” section in the CHAPTER 3.
*3 marked: Refer to “MAIN SWITCH INSPECTION” section.
NOTE:
Remove the following parts before inspection.
1) Seat
2) Rear fender
3) Fuel tank
Use 12 V battery in this inspection.
Use the following special tools in this inspection.
Pocket tester:
YU-3112-C/90890-03112
*1 Check fuseReplace fuse and
check wire harness.
*2 Check battery Recharge or replace.
Check each coupler and
wire connection.Repair or replace.
*3 Check main switch. Replace.
Check starter motor
operation.Repair or replace.
Check starting circuit
cut-off relay.Replace.
Check starter relay. Replace.
Check neutral switch. Replace.
Check start switch. Replace.
OK
OK
OK
OK
OK
OK
OK
OK
No good
No good
No good
No good
No good
No good
No good
No good
No good
ELECTRIC STARTING SYSTEM (TT-R90E)

–+ELEC
6 - 15
CHARGING SYSTEM (TT-R90E)
EC680000
CHARGING SYSTEM (TT-R90E)
EC681001
INSPECTION STEPS
If the battery is not charged, use the following inspection steps.
*1 marked: Refer to “FUSE INSPECTION” section in the CHAPTER 3.
*2 marked: Refer to “BATTERY INSPECTION AND CHARGING” section in the CHAPTER 3.
NOTE:
Remove the following parts before inspection.
1) Seat
2) Rear fender
3) Fuel tank
Use the following special tool in this inspection.
Pocket tester:
YU-3112-C/90890-03112Inductive tachometer:
YU-8036-B
Engine tachometer:
90890-03113
*1 Check fuse.Replace fuse and
check wire harness.
*2 Check battery. Recharge or replace.
Check each coupler and
wire connection.Repair or replace.
Check charging voltage.Charging system is
good.
Check CDI magneto. Lighting coil Replace.
Replace rectifier/regulator.
OK
OK
OK
No good
OK
No good
No good
No good
No good
OK

–+ELEC
6 - 17
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