I'm not sure if you are familiar with the shape of the top of an
expansion tank.  There is sort of a bump which fits into a sort of
socket at the top of the wheel well.  This, along with the tab that
goes over the stud, holds the thing up.  Two studs would have been
more secure and practical IMHO, but oh well...
   You have to wiggle it vigorously and pry gently at the tab that's
on the stud.  Once free from the stud, the tank will come out of the
socket and be free.  I can't swear that the filler tube won't
interfere because I've always had it out anyway when removing the exp
tanks.

Good luck,
Larry A.

On Sat, Jul 14, 2012 at 4:42 PM, Aaron Robinson
<a.robinson.lists@gmail.com> wrote:
> Hello all. I'm just pulling my expansion tank and it didn't fall out like I
> expected after removing the one nut and washer holding it on. I can rock
> it, but it won't come down and I don't want to break any of the old
> plastic. Can it be removed without moving the filler tube? I'm going to go
> and clean out all of the caked mud...that might be what's holding it all
> together!
>
> Thanks.
> Aaron
> '87 Westy