Topic: what part is this and does it have to be there

[guitarking135]

So I'm trying to figure out what this part is and the fiches don't show it anywhere. But it's the bulb thing on the bottom of the battery box. I'm building my cb750 into a bobber and I'm not sure what this bulb looking thing is

[wowbagger]

Photos and a model year will help immensely.

[bjbuchanan]

I'm guessing 77-78, its the separator. Think kinda like Pcv setup on a car. If you want to recycle engine fumes keep it, if you don't care dump it. You will have to re-route the hoses tho and plug the hole in the airbox

[guitarking135]

Plug the hole with say a crank case air filter type deal? or just like a rubber plug?

[flybox1]

you wont need it.
some attach a small air filter to a hose, and connect it to the nipple at the back of the valve cover.
this will allow you to eliminate the separator all together, but it will not provide a place for crank vapor to be re-burned (unless you decide to re-pipe it to a breadbox/airbox)