Honda TRX500FA 2006 Owner's Manual page 190

Suspension (TRX500FGA Canada only)
Position 1: for a light load and smooth road conditions.
Position 2: standard position.
Positions 3 to 5: for when the ATV is more heavily loaded. (Also
increase spring pre-load for stiffer suspension.)
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
181