2003 YAMAHA YZ125LC tow

4-44
ENG
KICK AXLE, SHIFT SHAFT AND PRIMARY DRIVE
GEAR
4. Hook:
9Torsion spring 1
NOTE:
Turn the torsion spring clockwise and hook into
the proper hole ain the crankcase.
EC4C5402
Kick idle gear
1. Install:
9Circlip 1
9Kick idle gear 2
9Plain washer 3
NOTE:
9Apply the transmission oil on the kick idle gear
inner circumference.
9Install the kick idle gear with its depressed side
atoward you.
EC4C5503
Primary drive gear
1. Install:
9Spacer 1
9Primary drive gear 2
9Bolt 3
NOTE:
Temporarily tighten the bolt at this point.
2. Install:
9Primary driven gear
Refer to “CLUTCH AND PRIMARY DRI-
VEN GEAR” section.
3. Tighten:
9Bolt (primary drive gear) 1
NOTE:
Place an aluminum plate abetween the teeth of
the primary drive gear 2and driven gear 3.
4. Install:
9Dowel pin 1
9Gasket [crankcase cover (right)] 2
55 Nm (5.5 m•kg, 40 ft•lb)

7-14
TUNSETTING
EC720000
CHASSISEC71P002
Selection of the secondary reduction ratio
(Sprocket)
Secondary Number of driven sprocket teethreduction =——————————————
ratioNumber of drive sprocket teeth
reduction ratio>
9It is generally said that the secondary gear ratio
should be reduced for a longer straight portion
of a speed course and should be increased for
a course with many corners. Actually, however,
as the speed depends on the ground condition
of the day of the race, be sure to run through
the circuit to set the machine suitable for the
entire course.
9In actuality, it is very difficult to achieve settings
suitable for the entire course and some settings
may be sacrificed. Thus, the settings should be
matched to the portion of the course that has
the greatest effect on the race result. In such a
case, run through the entire course while mak-
ing notes of lap times to find the best balance;
then, determine the secondary reduction ratio.
9If a course has a long straight portion where a
machine can run at maximum speed, the
machine is generally set such that it can devel-
op its maximum revolutions toward the end of
the straight line, with care taken to avoid the
engine over-revving.
NOTE:
Riding technique varies from rider to rider and
the performance of a machine also vary from
machine to machine. Therefore, do not imitate
other rider’s settings from the beginning but
choose your own setting according to the level of
your riding technique.
Standard secondary
49/13 (3.769)
reduction ratio

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).