2003 YAMAHA YZ125LC torque

2-12
SPEC
GENERAL TORQUE SPECIFICATIONS/
DEFINITION OF UNITS
This chart specifies torque for standard faste-
ners with standard I.S.O. pitch threads. Torque
specifications for special components or assem-
blies are included in the applicable sections of
this book. To avoid warpage, tighten multi-faste-
ner assemblies in a crisscross fashion, in pro-
gressive stages, until full torque is reached.
Unless otherwise specified, torque specifications
call for clean, dry threads. Components should
be at room temperature.
A: Distance across flats
B: Outside thread diameter
EC230000
DEFINITION OF UNITS
EC220001
GENERAL TORQUE SPECIFICATIONS
A B TORQUE SPECIFICATION
(Nut) (Bolt)
Nm m•kg ft•lb
10 mm 6 mm 6 0.6 4.3
12 mm 8 mm 15 1.5 11
14 mm 10 mm 30 3.0 22
17 mm 12 mm 55 5.5 40
19 mm 14 mm 85 8.5 61
22 mm 16 mm 130 13 94
Unit Read Definition Measure
mm milimeter 10-
3meter Length
cm centimeter 10-2meter Length
kg kilogram 103gram Weight
N Newton 1 kg ×m/sec2Force
Nm Newton meter N ×m Torque
m•kg Meter kilogrma m ×kg Torque
Pa Pascal N/m2Pressure
N/mm Newton per millimeter N/mm Spring rate
L Liter — Volume or capacity
cm3Cubic centimeter — Volume or capacity
r/min Revolution per minute — Engine speed

3-35
STEERING HEAD INSPECTION AND ADJUSTMENT
INSP
ADJ
2. Inspect:
9Bearing free play
Exist play Replace.
EC36U014
STEERING HEAD INSPECTION AND
ADJUSTMENT
1. Elevate the front wheel by placing a suitable
stand under the engine.
2. Check:
9Steering shaft
Grasp the bottom of the forks and gently
rock the fork assembly back and forth.
Free play Adjust steering head.
3. Check:
9Steering smooth action
Turn the handlebar lock to lock.
Unsmooth action Adjust steering ring
nut.
4. Adjust:
9Steering ring nut
Steering ring nut adjustment steps:
9Remove the number plate.
9Remove the handlebar and handle crown.
9Loosen the ring nut 1using the ring nut
wrench 2.
9Tighten the ring nut 3using ring nut wrench
4.
NOTE:
Set the torque wrench to the ring nut wrench
so that they form a right angle.
Ring nut wrench:
YU-33975/90890-01403

5-37
CHASFRONT FORK
2. Tighten:
9Cap bolt 1
3. Adjust:
9Front fork top end a
30 Nm (3.0 m•kg, 22 ft•lb)
Front fork top end (standard) a a
:
5 mm (0.20 in)
26. Tighten:
9Cap bolt (locknut) 1
NOTE:
9While compressing the fork spring, set the thin
type spanners 2between the spacer 3and
spring guide 4.
9Hold the locknut 5and tighten the cap bolt
with specified torque.
27. Install:
9Cap bolt 1
To outer tube.
NOTE:
Temporarily tighten the cap bolt.
28. Install:
9Protector guide 1
EC5552A1
Installation
1. Install:
9Front fork 1
NOTE:
9Temporarily tighten the pinch bolts (under
bracket).
9Do not tighten the pinch bolts (handle crown)
yet.
29 Nm (2.9 m•kg, 21 ft•lb)

5-38
CHASFRONT FORK
7. Adjust:
9Rebound damping force
NOTE:
Turn in the damping adjuster 1finger-tight and
then turn out to the originally set position.
4. Tighten:
9Pinch bolt (handle crown) 1
9Pinch bolt (under bracket) 2
cC
Tighten the under bracket to specified
torque. If torqued too much, it may cause
the front fork to malfunction.
5. Install:
9Brake hose holder 1
9Caliper 2
9Bolt (caliper) 3
NOTE:
Fit the brake hose holder cut aover the projec-
tion bon the front fork and clamp the brake
hose.
6. Install:
9Brake hose holder 1
9Bolt (brake hose holder) 2
9Protector 3
9Bolt (protector) 4
NOTE:
When installing the brake hose holder, align the
top aof the brake hose neck with the brake
hose holder bottom b. Then pass the brake
hose 5in front of the axle boss cand fit it into
the hose groove dso that the brake hose does
not contact the nut (wheel axle).
23 Nm (2.3 m•kg, 17 ft•lb)
20 Nm (2.0 m•kg, 14 ft•lb)
23 Nm (2.3 m•kg, 17 ft•lb)
10 Nm (1.0 m•kg, 7.2 ft•lb)
10 Nm (1.0 m•kg, 7.2 ft•lb)

5-50
CHASSTEERING
9. After tightening the nut, check the steering for
smooth movement. If not, adjust the steering
by loosening the ring nut little by little.
10. Adjust:
9Front fork top end a
11. Tighten:
9Pinch bolt (handle crown) 1
9Pinch bolt (under bracket) 2
cC
Tighten the under bracket to specified
torque. If torqued too much, it may cause
the front fork to malfunction.
Front fork top end (standard) a a
:
5 mm (0.20 in)
23 Nm (2.3 m•kg, 17 ft•lb)
20 Nm (2.0 m•kg, 14 ft•lb)

7-13
TUNSETTING
EC71X000
Selecting the rotor
If you feel the engine pick up faster depending
on the course condition, you can control it by
changing the rotor to the one with a greater iner-
tial mass.
* Inertial mass: The inertial mass of the body is
proportional to its weight and increases in pro-
portion to the square of the distance between its
rotation center and center of gravity. For the
same weight, a greater distance from its rota-
tion center produces greater inertial mass.
Greater initial mass gives a feeling of greater
torque in response to engine revolutions but is
accompanied by greater pick up resistance.
Engine characteristics are shown below in rela-
tion to each rotor:
9Standard rotor
Engine pickup is faster in the entire engine
speed range.
Pickup is fast at an extremely low engine
speed.
9Optional rotor
A feeling of torque is obtained at high engine
speed.
A broader power band is felt from mid speed to
over revs.
NOTE:
9Engine pick up differs according to the course
condition, rider, the settings, etc. Select a suit-
able rotor by comparing it with the standard
one in operation.
9It is difficult to be advantageous under all
course conditions with a change in the rotor.
Measure the lap times in accordance with race
points and select a rotor to produce a good
entire balance.
Part name Part number*Inertial mass
1 1
Standard rotor5CU-85550-11 0.0004kg•m2
2 2
Optional rotor5UN-85550-000.00045kg•m2

7-24
TUNSETTING
EC72H010
Suspension setting
9Front fork
NOTE:
9If any of the following symptoms is experienced with the standard position as the base, make reset-
ting by reference to the adjustment procedure given in the same chart.
9Before any change, set the rear shock absorber sunken length to the standard figure 90~100 mm
(3.5~3.9 in).
Section
Symptom
JumpLarge
Medium Small Check Adjust
gap gap gap
Compression damping Turn adjuster counterclockwise (about 2 clicks)
Stiff over entire to decrease damping.
range111Oil level (oil amount) Decrease oil level by about 5~10 mm (0.2~0.4
in).
Spring Replace with soft spring.
Unsmooth Outer tube Check for any bends, dents, and other notice-
movement over 1111Inner tube able scars, etc. If any, replace affected parts.
entire range
Under bracket tightening Retighten to specified torque.
torque
Poor initial Rebound damping Turn adjuster counterclockwise (about 2 clicks)
movement1to decrease damping.
Oil seal Apply grease in oil seal wall.
Compression damping Turn adjuster clockwise (about 2 clicks) to in-
Soft over entire crease damping.
range, bottoming 11Oil level (oil amount) Increase oil level by about 5~10 mm (0.2~0.4
outin).
Spring Replace with stiff spring.
Stiff toward stroke
1Oil level (oil amount) Decrease oil level by about 5 mm (0.2 in).
end
Soft toward stroke
1Oil level (oil amount) Increase oil level by about 5 mm (0.2 in).
end, bottoming out
Stiff initial
1111Compression dampingTurn adjuster counterclockwise (about 2 clicks)
movement to decrease damping.
Compression damping Turn adjuster clockwise (about 2 clicks) to in-
crease damping.
Low front, tending Rebound damping Turn adjuster counterclockwise (about 2 clicks)
to lower front 11to decrease damping.
postureBalance with rear end Set sunken length for 95~100 mm (3.7~3.9 in)
when one passenger is astride seat (lower rear
posture).
Oil level (oil amount) Increase oil level by about 5 mm (0.2 in).
Compression damping Turn adjuster counterclockwise (about 2 clicks)
to decrease damping.
“Obtrusive” front, Balance with rear end Set sunken length for 90~95 mm (3.5~3.7 in)
tending to upper 11when one passenger is astride seat (upper rear
front postureposture).
Spring Replace with soft spring.
Oil lever (oil amount) Decrease oil level by about 5~10 mm (0.2~0.4
in).