Yamaha WR450F(S) Owner's Service Manual page 740

T U N
SETTING
CAUTION:
When using a rear cushion other than cur-
rently 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.
Length a of standard shock:
490.5 mm (19.31 in)
Å Coverage of spring by weight
ı Rider weight
1 Soft
2 Standard
3 Stiff
7 - 18