2004 YAMAHA TTR90 maintenance

INTRODUCTION
Congratulations on your purchase of a
Yamaha TT-R90/TT-R90E. This model is the
culmination of Yamaha’s vast experience in
the production of pacesetting racing machines.
It represents the highest grade of craftsman-
ship and reliability that have made Yamaha a
leader.
This manual explains operation, inspection,
basic maintenance and tuning of your
machine. If you have any questions about this
manual or your machine, please contact your
Yamaha dealer.
NOTE:

As improvements are made on this model,
some data in this manual may become out-
dated. If you have any questions, please con-
sult your Yamaha dealer.
WARNING


READ THIS MANUAL CAREFULLY FOR
INSTRUCTIONS ON HOW TO PROPERLY
OPERATE THIS MACHINE.

ADULT INSTRUCTION AND SUPERVI-
SION ARE REQUIRED.

WEIGHT OF THE RIDER SHOULD NOT
EXCEED 40 kg (88 lb).

ALWAYS WEAR A HELMET AND SUIT-
ABLE PROTECTIVE CLOTHING WHEN
RIDING.

DO NOT TOUCH ANY MOVING PARTS OR
HEATED AREAS.

ALWAYS PERFORM PRE-OPERATION
CHECKS. REFER TO PAGE 3-2.

THIS MACHINE IS DESIGNED TO CARRY
THE OPERATOR ONLY.
NO PASSENGERS.

THIS MACHINE IS DESIGNED OFF-ROAD
USE ONLY.
IT IS NOT SUITABLE FOR ON-ROAD USE.

CONTENTS
CHAPTER 1
GENERAL INFORMATION
DESCRIPTION
.......................................... 1-1
MACHINE IDENTIFICATION
.................... 1-2
IMPORTANT INFORMATION
................... 1-3
CHECKING OF CONNECTION
................ 1-5
SPECIAL TOOLS
...................................... 1-6
CONTROL FUNCTIONS
........................... 1-9
FUEL
....................................................... 1-12
STARTING AND OPERATION
............... 1-13
CHAPTER 2
SPECIFICATIONS
GENERAL SPECIFICATIONS
.................. 2-1
MAINTENANCE SPECIFICATIONS
......... 2-4
GENERAL TORQUE
SPECIFICATIONS
.................................. 2-17
DEFINITION OF UNITS
.......................... 2-17
CABLE ROUTING DIAGRAM
................ 2-18
CHAPTER 3
REGULAR INSPECTION
AND ADJUSTMENTS
MAINTENANCE INTERVALS
................... 3-1
PERIODIC MAINTENANCE
AND LUBRICATION
................................. 3-1
PRE-OPERATION INSPECTION
AND MAINTENANCE
............................... 3-2
ENGINE
..................................................... 3-3
CHASSIS
................................................. 3-11
ELECTRICAL
.......................................... 3-20

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 (TT-R90)
....................... 4-39
CDI MAGNETO AND STARTER
CLUTCH (TT-R90E)
................................ 4-41
CRANKCASE AND CRANKSHAFT
....... 4-45
SHIFT FORK, SHIFT CAM
AND TRANSMISSION
............................ 4-48
CHAPTER 5
CHASSIS
FRONT WHEEL AND REAR WHEEL
...... 5-1
FRONT FORK
........................................... 5-6
HANDLEBAR
............................................ 5-9
STEERING
.............................................. 5-11
SWINGARM
............................................ 5-12
CHAPTER 6
ELECTRICAL
ELECTRICAL COMPONENTS
AND WIRING DIAGRAM
.......................... 6-1
IGNITION SYSTEM
................................... 6-3
ELECTRIC STARTING SYSTEM
(TT-R90E)
.................................................. 6-7
CHARGING SYSTEM (TT-R90E)
........... 6-15
CARBURETOR HEATING SYSTEM
...... 6-17
MAINTENANCE RECORD
..................... 6-21

1 - 11
GEN
INFO
CONTROL FUNCTIONS
FUEL COCK
The fuel cock supplies fuel from the tank to
carburetor while filtering the fuel. The fuel cock
has the three positions:
OFF: With the lever in this position, fuel will
not flow. Always return the lever to this
position when the engine is not running.
ON: With the lever in this position, fuel flows
to the carburetor. Normal riding is done
with the lever in this position.
RES: This indicates reserve. If you run out of
fuel while riding, move the lever to this
position. FILL THE TANK AT THE
FIRST OPPORTUNITY. BE SURE TO
SET THE LEVER TO “ON” AFTER
REFUELING.
STARTER LEVER (CHOKE)
When cold, the engine requires a richer air/fuel
mixture for starting. A separate starter circuit,
which is controlled by the starter lever 1, sup-
plies this mixture.
Pull the lever out to open the circuit (for start-
ing) and push the lever in to close the circuit.
FUEL TANK CAP
Remove the fuel tank cap 1 by turning
counter-clockwise.
WARNING
Do not overfill the fuel tank. Avoid spilling
fuel on the hot engine.
1
TOOL KIT
Spark plug wrench
Spark plug wrench 1 is used to remove and
install the spark plug.
Screw driver
This tool is used for preventive maintenance
and minor repairs.
1

SPEC

2 - 4
MAINTENANCE SPECIFICATIONS
ENGINE
Item Standard Limit
Cylinder head:
Warp limit ---- 0.03 mm
(0.0012 in)
Cylinder:
Bore size 47.000 ~ 47.005 mm
(1.8504 ~ 1.8506 in)47.05 mm
(1.8524 in)
Out of round limit ---- 0.05 mm
(0.0020 in)
Camshaft:
Drive method Chain drive (left) ----
Cam dimensions
Intake“A”25.428 ~ 25.528 mm
(1.0011 ~ 1.0050 in)25.400 mm
(1.0000 in)
“B”21.034 ~ 21.134 mm
(0.8281 ~ 0.8320 in)21.000 mm
(0.8268 in)
Exhaust“A”25.286 ~ 25.386 mm
(0.9955 ~ 0.9994 in)25.260 mm
(0.9945 in)
“B”21.047 ~ 21.147 mm
(0.8286 ~ 0.8326 in)21.017 mm
(0.8274 in)
Camshaft runout limit ---- 0.03 mm
(0.0012 in)
MAINTENANCE SPECIFICATIONS

SPEC

2 - 5 Cam chain:
Cam chain type/No. of links 92RH2005-84M/84 ----
Cam chain adjustment method Automatic ----
Rocker arm/rocker arm shaft:
Shaft outside diameter 9.981 ~ 9.991 mm
(0.3930 ~ 0.3933 in)9.95 mm
(0.3917 in)
Rocker arm inside diameter 10.000 ~ 10.015 mm
(0.3937 ~ 0.3943 in)10.03 mm
(0.3949 in)
Valve, valve seat, valve guide:
Valve clearance (cold) IN 0.05 ~ 0.09 mm
(0.0020 ~ 0.0035 in)----
EX 0.08 ~ 0.12 mm
(0.0031 ~ 0.0047 in)----
Valve dimensions:
“A” head diameter IN 22.9 ~ 23.1 mm
(0.9016 ~ 0.9094 in)----
EX 19.9 ~ 20.1 mm
(0.7835 ~ 0.7913 in)----
“B” face width IN 1.19 ~ 2.51 mm
(0.0469 ~ 0.0989 in)----
EX 1.49 ~ 3.07 mm
(0.0587 ~ 0.1209 in)----
“C” seat width IN 0.9 ~ 1.1 mm
(0.0354 ~ 0.0433 in)1.6 mm
(0.0630 in)
EX 0.9 ~ 1.1 mm
(0.0354 ~ 0.0433 in)1.6 mm
(0.0630 in)
“D” margin thickness IN 0.5 ~ 0.9 mm
(0.0197 ~ 0.354 in)----
EX 0.8 ~ 1.2 mm
(0.0315 ~ 0.0472 in)----
Stem outside diameter IN 4.475 ~ 4.490 mm
(0.1762 ~ 0.1768 in)4.450 mm
(0.1752 in)
EX 4.460 ~ 4.475 mm
(0.1756 ~ 0.1762 in)4.440 mm
(0.1748 in)
Guide inside diameter IN 4.500 ~ 4.512 mm
(0.1772 ~ 0.1776 in)4.542 mm
(0.1788 in)
EX 4.500 ~ 4.512 mm
(0.1772 ~ 0.1776 in)4.542 mm
(0.1788 in)
Stem-to-guide clearance IN 0.010 ~ 0.037 mm
(0.0004 ~ 0.0015 in)0.08 mm
(0.003 in)
EX 0.025 ~ 0.052 mm
(0.0010 ~ 0.0020 in)0.10 mm
(0.004 in) Item Standard Limit
Head Diameter
B
Face WidthC
Seat Width
D
Margin ThicknessA

MAINTENANCE SPECIFICATIONS

SPEC

2 - 6 Stem runout limit ---- 0.02 mm
(0.0008 in)
Valve seat width IN 0.9 ~ 1.1 mm
(0.0354 ~ 0.0433 in)1.6 mm
(0.0630 in)
EX 0.9 ~ 1.1 mm
(0.0354 ~ 0.0433 in)1.6 mm
(0.0630 in)
Valve spring:
Free length IN 32.45 mm (1.28 in) 26.9 mm
(1.06 in)
EX 32.45 mm (1.28 in) 26.9 mm
(1.06 in)
Set length (valve closed) IN 24.2 mm (0.95 in) ----
EX 24.2 mm (0.95 in) ----
Compressed pressure
(installed) IN 138 ~ 158 N
(14.07 ~ 16.11 kg,
31.02 ~ 35.52 lb)----
EX 138 ~ 158 N
(14.07 ~ 16.11 kg,
31.02 ~ 35.52 lb)----
Tilt limit IN ---- 2.5˚/1.4 mm
(2.5˚/0.06 in)
EX ---- 2.5˚/1.4 mm
(2.5˚/0.06 in)
Direction of winding
(top view) IN Clockwise ----
EX Clockwise ---- Item Standard Limit
*

MAINTENANCE SPECIFICATIONS

SPEC

2 - 7 Piston:
Piston to cylinder clearance 0.025 ~ 0.045 mm
(0.0010 ~ 0.0018 in)0.15 mm
(0.0059 in)
Piston size “D”46.960 ~ 46.975 mm
(1.8488 ~ 1.8494 in)----
Piston over size (2nd) 47.5 mm (1.8701 in) ----
(4th) 48.0 mm (1.8898 in) ----
Measuring point “H”4 mm (0.16 in) ----
Piston off-set 0.75 mm (0.0295 in) ----
Piston pin bore inside diameter 13.002 ~ 13.013 mm
(0.5119 ~ 0.5123 in)13.045 mm
(0.5136 in)
Piston pin outside diameter 12.996 ~ 13.000 mm
(0.5117 ~ 0.5118 in)12.980 mm
(0.511 in)
Piston rings:
Top ring
Type Barrel ----
Dimensions (B

×

T) 1.0
×
2.0 mm (0.04
×
0.08 in) ----
End gap (installed) 0.10 ~ 0.25 mm
(0.004 ~ 0.010 in)0.4 mm
(0.016 in)
Side clearance (installed) 0.030 ~ 0.065 mm
(0.0012 ~ 0.0026 in)0.12 mm
(0.005 in)
2nd ring
Type Taper ----
Dimensions (B

×

T) 1.0
×
2.0 mm (0.04
×
0.08 in) ----
End gap (installed) 0.10 ~ 0.25 mm
(0.004 ~ 0.010 in)0.4 mm
(0.016 in)
Side clearance 0.020 ~ 0.055 mm
(0.0008 ~ 0.0022 in)0.12 mm
(0.005 in)
Oil ring
Dimensions (B

×

T) 2.0
×
2.3 mm (0.08
×
0.09 in) ----
End gap (installed) 0.2 ~ 0.7 mm (0.01 ~ 0.03 in) ----Item Standard Limit
H
D
T
B
B
T
B
T

MAINTENANCE SPECIFICATIONS