I can't remember if the 650 forks can be lowered in the triple clamps. If they can, load her up and run it, then lower the front end 20mm and try it again.
A few of us have had similar issues with F800s and that seemed to fix it.
My F800 is significantly taller than standard, especially in the front. I think that with full knobbies as it has now it would be nearly uncontrollable without the steering damper.