First of all, your front tire can cause headshake, especially if it is cupped or the pressure if off (or if it's one of the special batch of Tourances :roll: ).
Other than the tire, check the fork clamps and steering nuts for proper torque. I don't have the numbers at hand but they're in the service manual. You'll need a spanner wrench, preferred, or a drift punch to get at the locknuts.
Personally, if I didn't have the torque values, spanners and the right size socket for the top nut, I would take it to a dealer and have them check it. Getting things wrong could make the problem worse or tweak the bearings.
06 DL-650 - SilverBlue
05 DL-650 - red (RIP - watch your mirrors!)