Just in case anyone was curious about how to take apart some 80s Honda OEM mirrors.
Locate the seem in the cap.
Pry the cap off gently with a knife.
There’s an 8mm nut, lock washer, and a fender washer.
The stem will now come directly up off of the mirror. You may need to rock it a bit.
Pro Tip: The difference between a Right-hand mirror and a Left-hand mirror is the direction the stem is facing when you put it on. So, if you’re looking on eBay for a left mirror and all you can find is a bunch of right mirrors, feel free to shop away.