Welcome to the site Kevin. The shims are standard 25mm shims. Available from your dealer. I got the data below from the tech vault, 11th post by Moe.
Valve Adjustments:
Yamaha Shims for the V-Max are direct replacements for Triumph shims.
SOB shims
25mm Used in Honda ('79--'83 4-cylinder CB750, 900, 1000, and 1100 series engines, and 1050 CBX 6-cylinder engines, and others), Yamaha (V-Max, and the FJ1100/1200 series), Triumph 3- and 4-cylinder liquid-cooled motorcycle engines, and older Toyota car engines.
