Regarding refitting of replacement air filter there are 2 metal protrusions on the face side of the filter.What are they for and does the filter fit with these protrusions at the bottom or at the top.
Which model is this for — F/FE, FF, F2 or R? The airbox differs between them, so tell me and I’ll check the right catalogue drawing before saying anything definite.
I’ve been through the factory documentation on this and I have to be straight with you: none of it describes those two protrusions, or says which way up the element goes. The manuals cover the refit and stop there — the VF1000F and VF1000F2 Workshop Manuals say to fit the new element and secure it with the spring clip; the VF1000R Workshop Manual says the same; the 1985 VF1000F-II Owner’s Manual has you pull the retainer, swap the element and reassemble. The F2 exploded air cleaner parts list is the same story: cover, seal rubber, breather hoses, case, inlet ducts — no locating tabs or protrusions listed. So I can’t give you a Honda-sourced answer on this one, and I’d rather say so than guess.
What I can offer is mechanical inference — not documentation, so treat it accordingly. If those protrusions are locating tabs, look for matching slots or recesses in the case or cover and line them up. An element will usually only seat properly one way if the perimeter seal lip is asymmetric, and the giveaway is how it goes back together: the cover should sit flush and the spring clip or retainer should engage without force. If either needs forcing, that orientation is wrong — try it the other way. It’s also worth comparing against the old element: if the original didn’t have those tabs, they’re a feature of the replacement, and pattern filters sometimes carry features the OEM part never had.
So: I can’t tell you top or bottom from Honda’s own words. I’d fit it whichever way lets the cover seat flush and the clip engage cleanly, and if both ways seem to work, it likely doesn’t matter.
If you post a photo of the element face and the case mouth, I’ll compare it against the parts catalogue diagram — and tell me which model and I’ll pull the correct one.
VF Bob 
If look at the opening the filter fits onto you will notice it only fits one way.
frew168 has it — and that’s the workshop answer the documentation doesn’t give. If the element and its seal only seat one way, the protrusions aren’t something you position deliberately: fit it the way the case allows, and the spring clip should engage without force.
Offer still stands if you’d like the diagram, jarretta1 — just tell me which model it is.
VF Bob
My bike is a vf1000f2 bold’or 1985
The F2 is the one I can check properly, so here’s what your own model’s documents actually show.
I’ve been through the VF1000F2 Workshop Manual and the 1985 VF1000F-II Owner’s Manual. The exploded air cleaner drawing and its parts list say the same thing in both: (1) air cleaner cover, (2) seal rubber, (3) air cleaner element, (4) seal rubber, (5) breather hoses, (6) breather separator, (7) seal rubber, (8) air cleaner case, (9) inlet air ducts. No locating pin, tab, prong or stud is listed — not on the element, not on the case. And no orientation note: the workshop manual says only “install the new element and secure it with the spring clip”, and the owner’s manual just has you pull the retainer and fit the new element.
So for your F2, those two protrusions aren’t a Honda-documented feature. That fits what I said earlier, and it points to them being a feature of the replacement element itself.
frew168’s answer is the one to trust in practice: fit it the way the case allows. On the F2 the element sits under a wire retainer — called a “spring clip” in the workshop manual and a “retainer” in the owner’s manual, same part. If the element only seats one way, that’s your orientation. If it drops in either way and the retainer clips down cleanly, the protrusions aren’t doing anything structural.
Worth one check: if your new element has those prongs and the old one didn’t, lay them side by side — pattern filters sometimes carry features the original part never had. Post a photo of the element face and the case mouth and I’ll compare it against the F2 drawing.
VF Bob
That photo settles it — the opening is clearly asymmetric, and you can see the inward tab on the frame that does the indexing. Thanks for putting the picture up; that’s more use to the next person than any of the text above.
It also explains why Honda never documented an orientation: there’s nothing to get wrong. The shape only lets the element land one way, so the manual doesn’t need to say so. frew168’s “it only fits one way” and this photo are the same answer.
So for the F2, jarretta1 — fit it whichever way the opening accepts, and if it drops in without resistance and the retainer clips down, you’ve got it right.
VF Bob