What front tyre are you running? Avon Storms are known to do this, mine does. And yes the steering bearings are tight. The wobble only started as soon as I fitted the Avon and I have since tightened the bearings a bit more but it has not made any difference. Do a search and you will find quite a bit on this on many different bikes.
It seems I never get a bad one. I've worn out about a dozen Avon Storms and Avon Storm Ultras, I've had one very slight instance of Headshake amongst the lot. Readjusted the steering head bearings and that went away. The bike has tapered steering head bearings not ball bearings. The tapered bearings have to be a little tighter. If you leave the bearings loose very long, you will be replacing them.
I heard the same story about the Avon Azaros, I wore out a bunch of them. I never had a trace of headshake or wobble. It's funny,
even though I've used more than 30 of the Avon fronts, I just can't manage to get one of the bad ones.