In the last couple of weeks I've watched some local Vet racers on KTMs on a local track.
It was evident that the #1 difference was rider skill, but very closely related was the suspension. One rider had apparently left his suspension at full woods soft, perfect for climbing over rocks and roots, but all wrong for jump. Anytime he got air it was frightening because the landing was a iffy thing - huge front end dive and lots of wallowing.
I don't know squat about suspension, but I know that this guy really needed to stiffen his up. Saw the same thing on some XRs brought to the track by the way.
I'd tell you to get as much practice time as possible, learn to rail the turns, which is where the races were won and lost.