Wondering what the thread size and pitch is of the Honda CX500, GL500, CX650, GL650 (and variants) crankcase bottle breather or inspection cover is? The inspection cover is found at the front of the motor and on the rear cover over the flywheel (for motors without the bottle breather in that location) and also on the final drive unit.
The bottle breather and inspection covers have identical thread diameter and pitch as they are interchangeable.
The inspection cover is Honda part number 12361-035-000, and the bottle breather part number is 12361-415-610 (see here for a bit more info on that.
Thread diameter:

Pitch:

This one appears to be from the time of the bike’s manufacture so it may be very slightly worn from the original size…