2001 YAMAHA YZ426F oil

6 - 9
–+ELEC

TPS (THROTTLE POSITION SENSOR) SYSTEM
TPS REPLACEMENT AND ADJUSTMENT
1. Remove:
l
TPS coupler
l
Screw (TPS)
1

l
Plain washer
2

l
TPS
3

2. Replace:
l
TPS
3. Install:
l
TPS
1

l
Plain washer
2

l
Screw (TPS)
3

l
TPS coupler
NOTE:

l
Align the slot
a
in the TPS with the projec-
tion
b
on the carburetor.
l
Temporarily tighten the screws (TPS).
4. Adjust:
l
Idle speed
Refer to “IDLE SPEED ADJUSTMENT”
section in the CHAPTER 3.
5. Calculate:
l
TPS coil resistance at idle speed.

If the TPS coil resistance is 5 k
W
, then the TPS
coil resistance at idle speed is:
5 k
W

´
(0.13 ~ 0.15) = 650 ~ 750
W
Refer to “TPS COIL INSPECTION” sec-
tion about the TPS coil resistance.
TPS coil resistance at idle speed:
TPS coil resistance
´
(0.13 ~ 0.15)

6 - 10
–+ELEC

TPS (THROTTLE POSITION SENSOR) SYSTEM
6. Adjust:
l
TPS coil resistance at idle speed
Adjustment steps:
Adjust the angle of the TPS
1
to obtain
the resistance calculated (example: 650 ~
750
W
)
Tester (+) lead
®
Yellow lead
2

Tester (–) lead
®
Black lead
3

7. Tighten:
l
Screw (TPS)
1

8. Install:
l
TPS coupler
EC694000
TPS INPUT VOLTAGE INSPECTION
1. Disconnect the TPS coupler.
2. Start the engine.
3. Inspect:
l
TPS input voltage
Out of specification
®
Replace the CDI
unit.
Tester (+) lead
®
Blue lead
1

Tester (–) lead
®
Black lead
2

TPS input
voltageTester selector
position
4 ~ 6 V DCV-20

7 - 12
TUNSETTING
EC722011
Front fork setting
The front fork setting should be made depend-
ing on the rider’s feeling of an actual run and
the circuit conditions.
The front fork setting includes the following
three factors:
1. Setting of air spring characteristics
lChange the fork oil level.
2. Setting of spring preload
lChange the spring.
lInstall the adjustment washer.
3. Setting of damping force
lChange the compression damping.
lChange the rebound damping.
The spring acts on the load and the
damping force acts on the cushion
travel speed.
EC723001
Change in level and characteristics of fork
oil
Damping characteristic near the final stroke
can be changed by changing the fork oil
amount.
CAUTION:
Adjust the oil level in 5 mm (0.2 in) incre-
ments or decrements. Too low oil level
causes the front fork to produce a noise at
full rebound or the rider to feel some pres-
sure on his hands or body. Alternatively,
too high oil level will develop unexpectedly
early oil lock with the consequent shorter
front fork travel and deteriorated perfor-
mance an characteristics. Therefore, adjust
the front fork within the specified range.
Air spring characteristics in relation to oil level
change
õLoad
‚Stroke
1Max. oil level
2Standard oil level
3Min. oil level
Standard oil level:
130 mm (5.12 in)
Extent of adjustment:
80 ~ 150 mm (3.15 ~ 5.91 in)
From top of outer tube with
inner tube and damper rod fully
compressed without spring.

7 - 20
TUN

SETTING
EC72H002
Suspension setting
l
Front fork
NOTE:

l
If any of the following symptoms is experienced with the standard position as the base, make
resetting by reference to the adjustment procedure given in the same chart.
l
Before any change, set the rear shock absorber sunken length to the standard figure 90 ~
100 mm (3.5 ~ 3.9 in).
SymptomSection
Check Adjust
JumpLarge
gap
Medium
gap
Small
gap
Stiff over entire range
CCC
Compression damping
Oil level (oil amount)
SpringTurn adjuster counterclockwise (about 2 clicks) to
decrease damping.
Decrease oil level by about 5 ~ 10 mm (0.2 ~ 0.4 in).
Replace with soft spring.
Unsmooth movement
over entire range
CCCC
Outer tube
Inner tube
Under bracket tightening
torqueCheck for any bends, dents, and other noticeable
scars, etc. If any, replace affected parts.
Retighten to specified torque.
Poor initial
movement
C
Rebound damping
Oil sealTurn adjuster counterclockwise (about 2 clicks) to
decrease damping.
Apply grease in oil seal wall.
Soft over entire range,
bottoming out
CC
Compression damping
Oil level (oil amount)
SpringTurn adjuster clockwise (about 2 clicks) to increase
damping.
Increase oil level by about 5 ~ 10 mm (0.2 ~ 0.4 in).
Replace with stiff spring.
Stiff toward stroke end
C
Oil level (oil amount) Decrease oil level by about 5 mm (0.2 in).
Soft toward stroke end,
bottoming out
C
Oil level (oil amount) Increase oil level by about 5 mm (0.2 in).
Stiff initial movement
CCCC
Compression dampingTurn adjuster counterclockwise (about 2 clicks) to
decrease damping.
Low front, tending to
lower front posture
CC
Compression damping
Rebound damping
Balance with rear end
Oil level (oil amount)Turn adjuster clockwise (about 2 clicks) to increase
damping.
Turn adjuster counterclockwise (about 2 clicks) to
decrease damping.
Set sunken length for 95 ~ 100 mm (3.7 ~ 3.9 in) when
one passenger is astride seat (lower rear posture).
Increase oil level by about 5 mm (0.2 in).
“Obtrusive” front, tend-
ing to upper front pos-
ture
CC
Compression damping
Balance with rear end
Spring
Oil lever (oil amount)Turn adjuster counterclockwise (about 2 clicks) to
decrease damping.
Set sunken length for 90 ~ 95 mm (3.5 ~ 3.7 in) when
one passenger is astride seat (upper rear posture).
Replace with soft spring.
Decrease oil level by about 5 ~ 10 mm (0.2 ~ 0.4 in).