Honda 2005 VTX1800C Owner's Manual page 140

The spring pre-load adjuster has
5 positions for different load or riding
conditions.
Use the pin spanner ( ) to adjust the rear
shock spring pre-load.
Position 1: for a light load and smooth
road conditions.
Position 2: standard position.
Positions 3 to 5: for when the
motorcycle is more heavily loaded.
(Also increase spring pre-load for
stiffer rear suspension.)
1
Make sure that both shock absorbers are
adjusted to the same position.
Always adjust the shock absorber position
in sequence (1-2-3-4-5 or 5-4-3-2-1).
Attempting to adjust directly from 1 to 5
or 5 to 1 may damage the shock absorber.
Servicing Your Honda
Suspension
131