Your design will appeal to the chopper folks. What about the bobber's, cafe's, street tracker's, dirt tracker's, stocker's?
Keep that one.
One without the choppers. Center the Yamaha XS650, change the skull for an XS650 engine, keep the "I built mine" centered underneath. It should appeal to more that way.
Several like that but say bobber, tracker, cafe, in place of the chopper. Maybe different center pieces instead of the skull.
Lots of custom tee shirt places can make them up in small lots. Do a couple different styles and let us see what they look like.
You can sell them here, on other 650 sites, Ebay.