seat adjustment YAMAHA TTR90 2003 Owners Manual

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

3 - 7
INSP
ADJ
PILOT AIR SCREW ADJUSTMENT
5. Install:
Gasket
Drain bolt
New
T R..20 Nm (2.0 m · kg, 14 ft · lb)
6. Fill:
Crankcase
Oil quantity:
Periodic oil change:
0.8 L (0.70 Imp qt, 0.85 US qt)
7. Install:
Dipstick
8. Inspect:
Engine (for oil leaks)
Oil level
Refer to “ENGINE OIL LEVEL INSPEC-
TION”.
PILOT AIR SCREW ADJUSTMENT
1. Adjust:
Pilot air screw 1
Adjusting steps:
Screw in the pilot air screw until it is lightly
seated.
Back out by the specified number of turns.
Pilot air screw:
1-3/4 turns out

4 - 5
ENG

CARBURETOR
EC464401
Jet needle
1. Inspect:

Jet needle
1
Bends/wear → Replace.
Clip groove
Free play exists/wear → Replace.
Clip position
Float height
1. Measure:
Float height a
Out of specification → Adjust.
Standard clip position:
No.2 Groove
Float height:
15.5 ~ 16.5 mm (0.61 ~ 0.65 in)
Measurement and adjustment steps:
Hold the carburetor in an upside down
position.
NOTE:
Slowly tilt the carburetor in the opposite
direction, then take the measurement
when the needle valve aligns with the float
arm.
If the carburetor is level, the weight of the
float will push in the needle valve, result-
ing in an incorrect measurement.
Measure the distance between the mating
surface of the float chamber and top of the
float using a vernier calipers.
NOTE:
The float arm should be resting on the nee-
dle valve, but not compressing the needle
valve.
If the float height is not within specifica-
tion, inspect the valve seat and needle
valve.
If either is worn, replace them both.
If both are fine, adjust the float height by
bending the float tab 1 on the float.
Recheck the float height.

4 - 6
ENGCARBURETOR
EC464600
Float
1. Inspect:
Float 1
Damage → Replace.
ASSEMBLY AND INSTALLATION
Carburetor
1. Install:
Pilot air screw 1
Note the following installation points:
Screw in the pilot air screw until it is lightly
seated.
Back out it by the specified number of
turns.
Pilot air screw:
1-3/4 turns out
2. Install:
Throttle valve 1
Starter plunger 2
NOTE:
Align the slit a of the throttle valve with the tab
b of the carburetor top.
FUEL LEVEL ADJUSTMENT
WARNING
Gasoline (fuel) and its vapors are highly
flammable and explosive. Keep away from
sparks, cigarettes, flames or other sources
of ignition.

4 - 32
ENGCLUTCH
ASSEMBLY AND INSTALLATION
Primary clutch
1. Install:
Washer 1
Nut (primary clutch) 2
NOTE:
Tighten the nut while holding the magneto
rotor with the sheave holder 3.
Clutch
1. Install:
Lock washer 1
Nut (clutch boss) 2
NOTE:
Use the clutch holding tool 3 to hold the clutch
boss.
ÅFor USA and CDN
ıExcept for USA and CDN
2. Bend:
Lock washer tab
Sheave holder:
YS-1880-A/90890-01701
Clutch holding tool:
YM-91042/90890-04086
T R..50 Nm (5.0 m · kg, 36 ft · lb)
New
T R..70 Nm (7.0 m · kg, 50 ft · lb)
Åı
Clutch release adjustment
1. Adjust:
Clutch release
Adjustment steps:
Loosen the locknut 1.
Turn in the adjuster 2 until it is lightly
seated.
Turn out by 1/8 turn.
Tighten the locknut.
T R..
Locknut:
8 Nm (0.8 m • kg, 5.8 ft • lb)