2003 YAMAHA TTR90 length

2 - 16
SPEC

GENERAL TORQUE SPECIFICATIONS/
DEFINITION OF UNITS
EC220001
GENERAL TORQUE SPECIFICATIONS
This chart specifies torque for standard fasten-
ers with standard I.S.O. pitch threads. Torque
specifications for special components or
assemblies are included in the applicable sec-
tions of this book. To avoid warpage, tighten
multi-fastener assemblies in a crisscross fash-
ion, in progressive stages, until full torque is
reached. Unless otherwise specified, torque
specifications call for clean, dry threads. Com-
ponents should be at room temperature.
A
(Nut)B
(Bolt)TORQUE
SPECIFICATION
Nm m•kg ft•lb
10 mm
12 mm
14 mm
17 mm
19 mm
22 mm6 mm
8 mm
10 mm
12 mm
14 mm
16 mm6
15
30
55
85
1300.6
1.5
3.0
5.5
8.5
134.3
11
22
40
61
94
A: Distance between flats
B: Outside thread diameter
EC230000
DEFINITION OF UNITS
Unit Read Definition Measure
mm
cmmillimeter
centimeter10
-3

meter
10
-2

meterLength
Length
kg kilogram 10
3

gram Weight
N Newton 1 kg
×
m/sec
2

Force
Nm
m • kgNewton meter
Meter kilogramN
×
m
m
×
kgTorque
Torque
Pa Pascal N/m
2

Pressure
N/mm Newton per millimeter N/mm Spring rate
L
cm
3

Liter
Cubic centimeter—
—Volume or capacity
Volume or capacity
r/min Revolution per minute—Engine speed

4 - 14
ENGCAMSHAFT AND ROCKER ARMS
REMOVAL POINTS
Rocker arm shaft
1. Remove:
Rocker arm shafts
NOTE:
Use a slide hammer bolt 1 and weight 2 to
slide out the rocker arm shafts.
Slide hammer set:
YU-1083-A
Slide hammer bolt:
90890-01085
Weight:
90890-01084
INSPECTION
Camshaft
1. Measure:
Cam lobes length a and b
Out of specification → Replace.
Cam lobes length limit:
Intake:
a 25.398 mm (0.9999 in)
b 21.004 mm (0.8269 in)
Exhaust:
a 25.256 mm (0.9943 in)
b 21.017 mm (0.8274 in)
ASSEMBLY AND INSTALLATION
1. Apply:
Molybdenum disulfide oil
(onto the camshaft cam lobe)
Engine oil
(onto the camshaft bearing)
2. Install:
Camshaft 1

4 - 18
ENGVALVES AND VALVE SPRINGS
Valve spring
1. Measure:
Valve spring free length a
Out of specification → Replace.
2. Measure:
Spring tilt a
Out of specification → Replace.
Free length (valve spring):
Intake:
32.45 mm (1.28 in)
: 26.9 mm (1.06 in)
Exhaust:
32.45 mm (1.28 in)
: 26.9 mm (1.06 in)
Spring tilt limit:
Intake:
2.5˚/1.4 mm (0.06 in)
Exhaust:
2.5˚/1.4 mm (0.06 in)
Valve seat
1. Measure:
Valve seat width a
Out of specification → Reface the valve
seat.
Valve seat width:
Intake:
0.9 ~ 1.1 mm (0.0354 ~ 0.0433 in)
: 1.6 mm (0.0630 in)
Exhaust:
0.9 ~ 1.1 mm (0.0354 ~ 0.0433 in)
: 1.6 mm (0.0630 in)
Measurement steps:
Apply Mechanic’s blueing dye (Dykem) b
to the valve face.
Install the valve into the cylinder head.
Press the valve through the valve guide
and onto the valve seat to make a clear
pattern.
Measure the valve seat width. Where the
valve seat and valve face made contact,
blueing will have been removed.
If the valve seat is too wide, too narrow, or
the seat is not centered, the valve seat
must be refaced.

4 - 31
ENGCLUTCH
EC484600
Clutch plate
1. Measure:
Clutch plate warpage
Out of specification → Replace clutch
plate as a set.
Use a surface plate 1 and thickness
gauge 2.
EC484400
Clutch spring
1. Measure:
Clutch spring free length a
Out of specification → Replace springs
as a set.
Push rod
1. Measure:
Push rod #2 bend
Out of specification → Replace.
Warp limit:
0.2 mm (0.008 in)
Clutch spring free length
Standard Limit
26.2 mm
(1.03 in)24.2 mm
(0.95 in)
Bending limit:
0.5 mm (0.02 in)
Primary clutch
1. Measure:
Primary clutch housing inside diameter
Out of specification → Replace.
Primary clutch housing inside
diameter:
105 mm (4.13 in)
: 106 mm (4.17 in)
2. Measure:
Clutch shoe groove depth a
Out of specification → Replace.
Clutch shoe groove depth:
1.0 ~ 1.3 mm (0.039 ~ 0.051 in)
: 0.1 mm (0.004 in)

6 - 13
–+ELEC
5. Measure:
Brush length a
Out of specification → Replace.
Brush length wear limit:
3.5 mm (0.14 in)
6. Measure:
Brush spring force
Fatigue/out of specification → Replace
as a set.
Brush spring force:
3.92 ~ 5.88 N
(400 ~ 600 g, 14.1 ~ 21.2 oz)
ASSEMBLY
1. Install:
Brush holder
2. Install:
Armature coil 1
3. Install:
Ring 1
Stator assembly 2
Front bracket 3
NOTE:
Apply molybdenum grease lightly on to the
bearings of the starter motor.
Align the match mark on the yoke with the
match mark on the bracket.
ELECTRIC STARTING SYSTEM