Go here:
http://www.vulcanforums.com/forums/showthread.php?t=72450&page=2
Same adjustment for a Custom as a Classic.
To make things easier, you can lift the bike a little to take the weight off the rear suspension - it's easier to go to a "softer" setting than a "firmer" setting, as you are not fighting the force of the spring in that direction.
http://www.vulcanforums.com/forums/showthread.php?t=72450&page=2
Same adjustment for a Custom as a Classic.
To make things easier, you can lift the bike a little to take the weight off the rear suspension - it's easier to go to a "softer" setting than a "firmer" setting, as you are not fighting the force of the spring in that direction.