Why do you want to take your hands off the handlebars at 40mph?
Going to the right might be something as simple as the cables, electrical / clutch or front brake pipe is helping that way, or possibly the front forks aren't settled correctly on the axle. Loosen the pinch bolt, bounce up and down a couple of times of the front forks and retighten the pinch bolt (there should be a gap between the spacer and the left-hand fork).
I'd try jacking up the rear preload somewhat as well, try it at max and see if there's any difference.