The CB1100 Community Forum

The design definitely accepts a paper filter inside.

However, it is possible the owner used a stainless steel re-usable oil filter that is simply rinsed (with mineral spirits) and blown dry and put back? My ol' Aprilia had a stainless steel filter cartridge in behind a spin-on cover.

Here's the correct OE finned oil filter enclosure. It's what I would have expected to see on this bike, especially considering the degree of restoration it went through. But again, it's possible I mistakenly saw something else because of the speed of the video.

No, LR, you’re right. The filter enclosure was smooth and polished.