Mine was looking like crap, with what seems like 16yo Sponge/Tar Like Sponge Stuff all inside.

I've cleaned, clearer and replaced the Filter, but what is it's purpose?

Does it actually do anything? Does it have to be there? I've never heard of it mentioned anywhere, the only reference in the Haynes Manual is the removal of the screw attaching it to the Air Box. It is on the Air Box Micro-Fiche though?

Confused & Bewildered

Iccle

yes its on the microfishe.
NC29 page F17, item number 8, honda PN: 17254-KAZ-000

like you i have wondered what its for, BUT it must be for sammat or they wouldent have fitted it.

Hi, From bikes I have had before its normally part of the emissions system, usually a pipe will come up from your crankcase into this sort of box, you can clean the gunk out as needed. But I admit I could be wrong, never looked into the NC29 to see what's what. Only if it needs fixing will I look, I'm leaving things like that until the Winter, must ride now the summers coming.