I have a Triumph Summer Screen on Karens bike and its centered. It has room for slight adjustment left to right, but not much.
My Alley Cat is as centered as it gets.

SOLD: 07 Black BA, 39mm FCRs, TPUSA stage 1 head, TPUSA 813 cams, TPUSA 10.8:1 pistons, TTP #3 igniter, Specialty Spares Long Cannons, Tsukayu Hard Bags. 82HP/55tq NEW: 19 Goldwing Tour DCT