Front Fork Setting Parts; Rear Suspension Setting; Choosing Set Length - Yamaha YZ450FX 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 4.1 B3J-23141-10
4.2 B3J-23141-20
4.3 B3J-23141-30
4.4 B3J-23141-40
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.
4.6
I.D.
mark
(slits)
III
IIII
IIIII
I-I
I-II
I-III
EAM30175

REAR SUSPENSION SETTING

I-IIII
The rear shock absorber setting should be made
depending on the rider's feeling of an actual run
I-IIIII
and the circuit conditions.
II-II
The rear suspension setting includes the follow-
II-III
ing two factors:
1. Setting of spring preload
II-IIII
• Change the set length of the spring.
• Change the spring.
2. Setting of damping force
• Change the rebound damping force.
• Change the compression damping force.
EAM30176

CHOOSING SET LENGTH

1. Place a stand or a block under the engine to
2. Remove the stand or block from the engine
10-3
a
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
CHASSIS
1
a