Yamaha yz250 2015, Owner'S Manual

Page: 170 / 174

7-8
CHASSIS
CHOOSING SET LENGTH
1. Place a stand or block under the
engine to put the rear wheel
above the floor, and measure the
length "a" between the rear wheel
axle center and the rear fender
holding bolt.
2. Remove the stand or block from
the engine and with a rider astride
the seat, measure the sunken
length "b" between the rear wheel
axle center and the rear fender
holding bolt.
3. Loosen the locknut "1" and make
adjustment by turning the spring
adjuster "2" to achieve the stan-
dard figure from the subtraction of
the length "b" from the length "a".
• If the machine is new and after it is
broken in, the same set length of
the spring may change because of
the initial fatigue, etc. of the spring.
Therefore, be sure to make reeval-
uation.
• If the standard figure cannot be
achieved by adjusting the spring
adjuster and changing the spring
set length, replace the spring with
an optional one and make readjust-
ment.
SETTING OF SPRING AFTER
REPLACEMENT
After replacement, be sure to adjust
the spring to the set length [sunken
length 90–100 mm (3.5–3.9 in)] and
set it.
1. Use of soft spring
• Set the soft spring for less re-
bound damping to compensate
for its less spring load. Run with
the rebound damping adjuster
one or two clicks on the softer
side and readjust it to suit your
preference.
2. Use of stiff spring
• Set the soft spring for more re-
bound damping to compensate
for its greater spring load. Run
with the rebound damping adjust-
er one or two clicks on the stiffer
side and readjust it to suit your
preference.
Adjusting the rebound damping will
be followed more or less by a change
in the compression damping. For cor-
rection, turn the low compression
damping adjuster on the softer side.
When using a rear shock absorber
other than currently installed, use
the one whose overall length "a"
does not exceed the standard as it
may result in faulty performance.
Never use one whose overall
length is greater than standard.
REAR SHOCK ABSORBER
SETTING PARTS
• Rear shock spring "1"
[Equal-pitch steel spring]
[Unequal-pitch steel spring]
• The unequal-pitch spring is softer in
initial characteristic than the equal-
pitch spring and is difficult to bottom
out under full compression.
• The I.D. mark "a" is marked at the
end of the spring.
• Spring specification varies accord-
ing to the color and quantity of I.D.
marks.
Standard figure:
90–100 mm (3.5–3.9 in)
Length "a" of standard
shock:
490 mm (19.29 in)
TYPE
SPRI
NG
RAT
E
SPRING
PART
NUM-
BER
(-22212-)
I.D.
MARK/
Q'TY
SOFT
4.3 5UN-00 Brown/1
4.4 5UN-10 Green/1
4.7 5UN-20 Red/1
STD 4.9 5UN-30 Black/1
5.1 5UN-40 Blue/1
STIFF
5.3 5UN-50 Yellow/1
5.5 5UN-60 Pink/1
5.7 5UN-70 White/1
TYPE
SPRI
NG
RATE
(ap-
prox.)
SPRING
PART
NUM-
BER
(-22212-)
I.D.
MARK/
Q'TY
SOFT 4.5 5UN-A0 Green/2
4.7 5UN-B0 Red/2
4.9 5UN-C0 Black/2
5.1 5UN-D0 Blue/2
STIFF
5.3 5UN-E0 Yellow/2
5.5 5UN-F0 Pink/2
5.7 5UN-G0 White/2