There is a small hose nipple on the backplate of the Ham Can airbox.
Can anyone tell me, or better yet show me, where it goes to?

 

If you mean the giant, post '79 Mailbox air cleaner... that had the Crank vent plumbed to it originally...

 

Yes, what racepres said. Part of the EPA / C.A.R.B. crap at the time. I plugged mine on my 84. Not as though you are gonna get pulled over on a Shovel today for a roadside inspection.

 

I know what the large one up near the carb mounting is for, the vent hose like you say.
I'm talking about the small nipple that is at the bottom.
in the picture it's got tape over it.

 

It's much smaller diameter than the vent hose.

 

LOL
Well...maybe in CommieFornia...Easy Now... thats [kind of] a joke Son!!!
I believe the practice of feeding the Crank vent right into the carb, lasted thru the EVO years!!!!!

 

My 85 Evo Wide Glide was vented to air cleaner.

But what's the small hose nipple for that's pictured above?
I've had several of those air cleaners and they all have it.

 

I wonder if it could be a drip hose for excess oil vented to air cleaner??

 

I found a diagram that showed it as an overflow hose (3/16), with a plug in the bottom.

 

Oh ****... that little bity hose toward the outside... Drain... fuel, excess oil, water... etc..
I was thinking of the larger [3/8] barb closer to the intake... for Crank Vent...

If you ever watched the standoff of the Ka-Sneeze carb you understand "fuel"... Oil, from Crankcase vent. And Water, is sort of a stretch if the "box" is assembled properly, with all of the pieces and parts...