Yamaha YZ450F(S) Owner's Service Manual page 622

SETTING
2. Use of stiff spring
Generally a stiff spring gives a stiff riding
feeling. Rebound damping tends to
become weaker, resulting in lack of a
sense of contact with the road surface or
in a vibrating handlebar.
To set a stiff spring:
Change the rebound damping.
G
Turn in one or two clicks.
Change the compression damping.
G
Turn out one or two clicks.
Å Coverage of spring by weight
ı Rider weight
1 Soft
2 Standard
3 Stiff
7 - 16
T U N