From the list at IBMWR.org, with a few annotations from me (wmax351).
Purolator air filter for K75 / K100 air filter
Date: Sat, 16 May 1998 11:23:36 -0500 (CDT)
From: Rick Landi <
RLandi@ix.netcom.com>
I'm using a paper filter from Purolator, model AF-3389, that replaces the stock filter perfectly. I don't know where they came from, how much they cost, or whether they are still available but...
Since I have two left and only replace the filter annually, the answers to these questions haven't been a priority for me. Oh, BTW, the fitment info on the box says BMW Motorcycles K-100 models.