All current Husqvarna and KTM motocross bikes come fitted with a WP air-spring fork. We have tested every production air fork that’s been made and believe WP has created the best yet.
The big bonus with these forks is that the spring rate can be adjusted in just minutes with an air pump rather than having to disassemble the fork and change coil springs. This means they can be adjusted at the track easily to tune the bike to the layout and conditions.
1 PIT STAND
Start by putting the bike on a pit stand with the front wheel off the ground. If the tyre is on the deck and the fork is partly compressed then the psi reading on the pump will be higher and you will have an inaccurate figure.
2 REMOVE VALVE CAP
Remove the cap from the Schrader valve on top of the left fork cap. These can sometimes be tight. You may need to remove the handlebar pad to get better access.
3 POWER BUTTON
Screw the pump onto the valve, gently until it is seated. Then press the power button on the pump to turn it on and get a pressure reading.
4 PUMP THE HANDLE
Adjust the psi up or down by pumping the handle or by pressing the bleed button on the pump and letting air out until you reach the desired pressure.
5 BE QUICK
Once you have reached the pressure you want, remove the pump. You will need to unscrew the pump hose and remove it quickly so you do not lose pressure from the fork. If you unscrew it too slowly air will leak out and you’ll have less pressure than the reading you got.
6 O-RING
Make sure the rubber O-ring is still inside the valve cap and refit it on the valve stem.
7 BLEED SCREWS
On both fork caps there are bleed screws which release built up air in the outer chambers just as on a conventional coil-spring fork. These need to be bled out just like a normal fork. Unscrew the Torq screws until you hear a hiss of air and then retighten them. This can be done after each ride to stop air building up in the outer chambers. ADB Tech Ed Mat Boyd
Tips for tuning an Air Fork
DO’S
1 Screw the pump hose on and off quickly.
2 Always have the front wheel off the ground.
3 Use only a proper shock absorber pump.
DON’TS
1 Hook up an air compressor hose to the fork. It may damage the internals.
2 Change air settings too much. Just change in small increments and test.
3 Use anything other than a shock pump.
