Try our new info resource - "Aladdin's Cave" (Main menu)Just added a separate link to Ash's Dropbox thread (shortcut)
I think it was possibly dropped before the K1s, but it does show on all the parts lists K0, K1, K2.One thing I have never seen is a rubber bit over the front top of the air cleaner shown on the p/l.17315-323-000. According the parts list it was fitted to countries A, D, E, F. Clauss Studios sell it.
I have my airfilter case apart and forgot how that part (17318-323-000) should be oriented. You have to look well, but the pic in the CB500K2 (ED, F, G) parts list seems to suggest it protrudes into the chamber and not into the hole. https://images.cmsnl.com/img/partslists/honda-cb500k2-general-export-f-16-air-cleaner_big3IMG01171138_b55e.gif Is that right?
... and the filter is slanted at the front to accommodate it.