I heard about the 3.5" problem before I installed my 3.5", but before I ordered the 4.5". Just in case while doing the install, I got oversized nuts (just over 1" wide) from home depot and longer bolts. I installed the 3.5" and saw they made contact, so I placed the nuts between the risers and the triple tree. This held me over until the 4.5" risers came in.EDITED
I take it that like me, you never installed the 3.5" risers because you found out they would be a problem with the clearance of the speedo housing?
This is after I got the 4.5" Risers: