2001 YAMAHA TTR90 maintenance

INTRODUCTION
Congratulations on your purchase of a
Yamaha TT-R90(N). This model is the culmi-
nation of Yamaha’s vast experience in the pro-
duction of pacesetting racing machines. It
represents the highest grade of craftsmanship
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

l
READ THIS MANUAL CAREFULLY FOR
INSTRUCTIONS ON HOW TO PROPERLY
OPERATE THIS MACHINE.
l
ADULT INSTRUCTION AND SUPERVI-
SION ARE REQUIRED.
l
WEIGHT OF THE RIDER SHOULD NOT
EXCEED 40 kg (88 lb).
l
ALWAYS WEAR A HELMET AND SUIT-
ABLE PROTECTIVE CLOTHING WHEN
RIDING.
l
DO NOT TOUCH ANY MOVING PARTS OR
HEATED AREAS.
l
ALWAYS PERFORM PRE-OPERATION
CHECKS. REFER TO PAGE 15.
l
THIS MACHINE IS DESIGNED TO CARRY
THE OPERATOR ONLY.
NO PASSENGERS.
l
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
....................................................... 1-11
STARTING AND OPERATION
............... 1-12
CHAPTER 2
SPECIFICATIONS
GENERAL SPECIFICATIONS
................... 2-1
MAINTENANCE SPECIFICATIONS
......... 2-4
GENERAL TORQUE
SPECIFICATIONS
.................................. 2-15
DEFINITION OF UNITS
.......................... 2-15
CABLE ROUTING DIAGRAM
................ 2-16
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
.......................................... 3-19

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

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)25.328 mm
(0.9972 in)
“B” 21.034 ~ 21.134 mm
(0.8281 ~ 0.8320 in)20.934 mm
(0.8242 in)
Exhaust “A” 25.286 ~ 25.386 mm
(0.9955 ~ 0.9994 in)25.186 mm
(0.9916 in)
“B” 21.047 ~ 21.147 mm
(0.8286 ~ 0.8326 in)20.947 mm
(0.8247 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)4.435 mm
(0.1746 in)
Guide inside diameter IN 4.500 ~ 4.512 mm
(0.1772 ~ 0.1776 in)4.550 mm
(0.1791 in)
EX 4.500 ~ 4.512 mm
(0.1772 ~ 0.1776 in)4.550 mm
(0.1791 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 28.32 mm (1.11 in) 26.9 mm
(1.06 in)
EX 28.32 mm (1.11 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 90.4 ~ 104.1 N
(9.2 ~ 10.6 kg, 20.32 ~ 23.40 lb)----
EX 90.4 ~ 104.1 N
(9.2 ~ 10.6 kg, 20.32 ~ 23.40 lb)----
Tilt limit IN ---- 2.5˚/1.2 mm
(2.5˚/0.05 in)
EX ---- 2.5˚/1.2 mm
(2.5˚/0.05 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)12.976 mm
(0.5109 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

SPEC

2 - 8
Crankshaft:
Crank width “A” 42.95 ~ 43.00 mm
(1.691 ~ 1.693 in)----
Runout limit C ---- 0.03 mm
(0.0012 in)
Big end side clearance “D” 0.10 ~ 0.40 mm
(0.0039 ~ 0.0157 in)0.50 mm
(0.02 in)
Big end radial clearance “E” 0.010 ~ 0.025 mm
(0.0004 ~ 0.0010 in)0.05 mm
(0.002 in)
Clutch:
Friction plate thickness 2.7 ~ 2.9 mm
(0.106 ~ 0.114 in)2.6 mm
(0.102 in)
Quantity 5 ----
Clutch plate thickness 1.1 ~ 1.3 mm (0.043 ~ 0.051 in) ----
Quantity 4 ----
Warp limit ---- 0.2 mm
(0.008 in)
Clutch spring free length 26.2 mm (1.03 in) 24.2 mm
(0.95 in)
Quantity 4 ----
Clutch release method Inner push, cam push ----
Push rod bending limit ---- 0.5 mm
(0.02 in)
Automatic centrifugal clutch: ----
Clutch-in revolution 2,160 ~ 2,560 r/min ----
Clutch-stall revolution 3,300 ~ 3,800 r/min
Shifter:
Shifter type Cam drum and guide bar ----
Kick starter:
Type Ratchet type ----
Kick clip friction force 5.8 ~ 14.7 N
(0.59 ~ 1.50 kg, 1.3 ~ 3.3 lb)
Carburetor:
I. D. mark 5HN1 01 ----
Main jet (M.J) #90 ----
Main air jet (M.A.J) ø 1.1 ----
Jet needle (J.N) 4E9-2 ----
Cutaway (C.A) 2.5 ----
Pilot outlet (P.O) ø 1.0
´
2.0 ----
Pilot jet (P.J) #12.5 ----
Valve seat size (V.S) ø 1.5 ----
Starter jet 1 (G.S.1) #37.5 ----
Pilot air screw 1-3/4 turns out
Float height (F.H) 15.5 ~ 16.5 mm (0.61 ~ 0.65 in) ----
Fuel level (F.L) 2 ~ 3 mm (0.08 ~ 0.1 in) ----
Engine idle speed 1,400 ~ 1,600 r/min ----Item Standard Limit
MAINTENANCE SPECIFICATIONS
CC
D
A
E