They sell mirror extenders for a price. They extend and raise the mirrors.
If all you want is to extend the mirrors, you can make your own extenders.
Buy some 1"x1/4" aluminum bar stock (uusually 1 or 2 ft long).
Cut a couple of 2.5" pieces. Drill an appropriate sized hole near each end of the piece.
Buy metric nuts, lock and flat washers and bolts. Use the bolts to mount the Al pieces to the original mirror mounts.
Use the washers and nuts to mount the mirrors to the other end of the Al. pieces.
If you care, you can round the corners of the pieces with a sander and spray paint them black.
ExTex: 2015 CB500 FA, 1989 Inteceptor VTR 250
Sold: CB650sc, VF700s, VT500c, Ninja 500