Front Fork Setting Parts; Rear Suspension Setting; Choosing Set Length - Yamaha YZ250FM 2021 Owner's Service Manual

TIP
Generally a stiff spring gives a stiff riding feeling.
Rebound damping tends to become weaker, re-
sulting in lack of a sense of contact with the road
surface or in a vibrating handlebar.
EAM30174

FRONT FORK SETTING PARTS

• Front fork spring "1"
STD Spring rate
N/mm
Spring
Type rate Part number
N/mm
SOFT 4.5 BR9-23141-20
4.6 BR9-23141-30
4.7 BR9-23141-40
4.8 BR9-23141-50
4.9 BR9-23141-60
5.0 BR9-23141-70
STIFF 5.1 BR9-23141-80
TIP
The I.D. mark (slits) "a" is proved on the end of
the spring.
a
EAM30175

REAR SUSPENSION SETTING

The rear shock absorber setting should be made
depending on the rider's feeling of an actual run
and the circuit conditions.
The rear suspension setting includes the follow-
ing two factors:
1. Setting of spring preload
2. Setting of damping force
4.7
EAM30176

CHOOSING SET LENGTH

1. Place a stand or a block under the engine to
I.D.
mark
(slits)
I-II
I-III
I-IIII
I-IIIII
II-II
II-III
II-IIII
2. Remove the stand or block from the engine
3. Loosen the locknut "1" and make adjustment
1
TIP
• If the machine is new and after it is broken in,
10-3
• Change the set length of the spring.
• Change the spring.
• Change the rebound damping force.
• Change the compression damping force.
put the rear wheel above the floor, and mea-
sure the length "a" between the rear wheel
axle center and the rear fender holding bolt.
and, with a rider astride the seat, measure the
sunken length "b" between the rear wheel
axle center and the rear fender holding bolt.
by turning the adjuster "2" to achieve the
standard figure from the subtraction of the
length "b" from the length "a".
Standard figure
90–100 mm (3.5–3.9 in)
the same set length of the spring may change
because of the initial fatigue, etc. of the spring.
Therefore, be sure to make reevaluation.
CHASSIS
a
b