After testing initially we quickly learned not to lower the rear end of this bike. Stick to the recommended KTM setup of 105mm rider sag (rider including gear) / 35mm static sag to keep the fork and shock working together.
If you don’t, this KTM will be a wild bucking machine. We changed to the optional hard rear spring (45nm) to achieve this on the 350SXF with a rider weight of 88 kg+ gear. Not only did it hold the rear up and improve drive through the bumps we had great results on corner entry with a more positive fork and shock action.
Testing on the 250SXF we went the other way with our test rider running a softer spring to achieve the correct 105mm rider sag with a 65 kg rider. KTM recommend a 75-85kg rider for their stock settings. Outside of this window including gear and you will need to change the spring/air setup.
After riding the bike stock on a square edged baked track we quickly experienced headshake and fork chatter at high breaking speeds. This unnerving action is due to the hard fork ‘valving’ setting, not chassis in-balance. We counter intuitively slid the forks up to 3 lines thru the top clamp to get more weight onto the front wheel, softened the comp clicker 3-4 clicks and loosened the rebound clicker out 2 clicks. Problem improved.
We lowered the Air pressure to help here also, but found if we moved it too much and we were bottoming on the landings plus we experienced a divey feel in the front end under braking. Nothing unusual here. The fix, revalve the fork to a plusher setting. Deep Sand tracks will handle the hard and high running AER fork much better. Test back at the stock 2 lines thru fork height in this case.