One of the best reasons to ride a Harley-Davidson FL model is for the supple ride. There's not a bike in the lineup that affords the rider a smooth, responsive ride while still having the ability to soak up bumps in the road with ease. The problem with many riders is that they very rarely, if ever, check the air pressure in the stock rear shocks, even though it's critical to not only a good ride but also, more importantly, a stable, predictable, and safe ride.
The shocks are designed to work over a large range of air pressures, thus allowing you the ability to fine-tune the suspension based on how much weight you place on the bike. They are not designed to change the ride height of the bike for purely cosmetic reasons. Adding air pressure within the shocks' limits gives you the ability to add more weight on the bike while still maintaining a high-quality ride.
Checking the air pressure and making adjustments to the system is really quite simple. There is an air fitting located behind the right saddlebag on pre-'06 models and on the left side on '06 models. Air is introduced to the system via this Schrader-style valve with a hand-held air pump, available from Harley (the Touring Suspension Air Pump; part No. 54630-03A, MSRP: $39.95). The pump comes complete with a gauge so you are able to monitor exactly how much air is in the system. Since the shocks hold a very small volume of air, the pressure increases or decreases very quickly as air is introduced to or removed from the system.
Considering that there's always more than one way to skin a cat, we scrounged up some parts lying around the shop and put together an assembly that would allow us to precisely control the air pressure in the system, utilizing compressed air from the shop. It is simply a pressure regulator with a gauge on the low-pressure side, a needle valve, and an air chuck to introduce air into the system.
0-10 lbs for a 150-lb to 200-lb rider.5-15 lbs for a 200-lb to 250-lb rider.20-25 lbs for a rider with passenger.FL air preload rear suspension range is 0-35 lbs of pressure.FLHRS and FLXH low-profile shocks are 0-50 lbs max.
 Filling the shocks to the...  Filling the shocks to the proper pressure with Harley's pump is as simple as removing the saddlebag, connecting the airline, and pumping up the system to the desired pressure. |  Here we used our homemade...  Here we used our homemade regulator/air-chuck assembly on an '06 model to control precisely how much air is contained in the system. This is done by adjusting the regulator within the pressure range of the shocks. | |