First, i have to say congrats on your hybrid...You will like her alot..That piece is like a breather I guess you would say..I have a rubber hose that comes from there,and ran in along the top of my subframe to the back and put 1 of those mini breather filter to the end of it..Do you need the filter not really,I just put it there because I had one laying around,and I have access to cleaning it..By the way,Honda does not sell that little nipple seperatly,you have to buy the whole head just incase it gets messed up or something..Mine had a little wear on the top of from the gas tank rubbing on it,not a biggy at all,they told me I had to buy the whole head,so i just told them to go "pound sand"..Mine was good enough..Good luck,and post some pics of your new ride..
LSR/CRF450
JB ex w/yz450dirtbike motor
Thats right "hybrids the only way to go....They go BRAAAAAAAPPP..