Honda FOREMAN RUBICON TRX500FM6 2018 Owner's Manual page 171

Suspension
Suspension Spring Pre-Load
Refer to Safety Precautions on page 109.
FRONT
(1)
1 2 3 4 5
(1) spring pre-load adjuster
(2) pin spanner
The spring pre-load adjuster (1) has 5 positions for different load or
riding conditions.
Use the pin spanner (2) to adjust the shock spring pre-load.
164
Servicing Your Honda
REAR
(2)
1 2 3
(2)
(1)
4 5