I apologize for the confusion, but the Benelli SBE3 is a semi-automatic shotgun, not a motorcycle.
To change shims on a Benelli SBE3 shotgun, I recommend referring to the owner's manual that came with your firearm. The manual should contain detailed instructions and diagrams specific to your shotgun model, including information on changing shims.
If you don't have the manual or need further assistance, I suggest reaching out to Benelli customer support or contacting a qualified gunsmith who can provide you with the necessary guidance and instructions for changing shims on your Benelli SBE3 shotgun.