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Changing the Bottom-Out Control Pressure BUY IT

Figure 1: FOX High Pressure Pump

Adjusting the Effective Range for the Bottom Out Control

The bottom out control valve provides position-sensitive end stroke damping. This allows for a seamless transition from small bumps to big drop bottom outs. The Bottom Out valve is not adjusted directly. Instead, its behavior and performance characteristics are influenced by the air pressure setting in the reservoir and by adjusting the reservoir Bottom Out Control knob.

To change the range of Bottom Out Control damping characteristics of your DHX RC4 shock, attach a FOX High Pressure Pump to the air valve on the reservoir.

NOTE: The factory pressure setting is 160 PSI.

For more bottom out resistance, add 10–15 pounds of air pressure, to a maximum of 200 PSI.
For less bottom out resistance, decrease the shock’s air pressure 10–15 pounds with the pump’s bleed valve, to a minimum of 125 PSI.

Ride your bike and verify the settings, before repeating the procedure.

Changing Bottom Out Control Reservoir Pressure

Remove the air cap from the reservoir.
Connect the pump by threading the chuck onto the Schrader valve until the pump gauge registers pressure. This takes about 6 turns. If the fork has no air pressure, the gauge will not register. Do not over-tighten the chuck, as it can damage the pump chuck seal.
Increase the pressure by stroking the pump a few times; the pressure should increase slowly. If the pressure increases rapidly, check that the pump is properly connected to the Schrader valve.
Decrease the pressure by depressing the black bleed valve. Push the bleed valve in halfway and hold, to allow continuous pressure release. Depress the bleed valve completely to release pressure incrementally (micro adjust).
Disconnect the pump by unthreading the chuck.
NOTE: The hiss sound of air loss comes from the pump hose, not the fork.
Install the air cap, and go ride.
CAUTION: Never ride your bike with more than 200 PSI or less than 125 PSI in the DHX RC2 reservoir air chamber. Doing this can damage your shock, requiring repairs that are not covered under terms of the warranty. In racing applications, FOX Racing Shox uses nitrogen gas in the reservoir. For every day riding, air from the hand pump works fine; after all, it's ~78% nitrogen anyway.