Make sure your bars don't have a slit.
What headset are you using? Make sure your crown race is on right, the bearings are in right, headset all the way in, top cap all the way down, etc.
What fork?
If the SCS has ever been ridden on threaded forks the inside could be messed up and too large causing the wobble.
Hit your starnut in a little further.
Hammer the SCS down with a rubber mallet and tighten the compression bolt more.
What headset are you using? Make sure your crown race is on right, the bearings are in right, headset all the way in, top cap all the way down, etc.
What fork?
If the SCS has ever been ridden on threaded forks the inside could be messed up and too large causing the wobble.
Hit your starnut in a little further.
Hammer the SCS down with a rubber mallet and tighten the compression bolt more.