1984 vf750f coolant expansion tank connection question

Putting back together and I notice a nipple on the bottom of the rear expansion tank (sits on the rear wheel arch protector, just behind the fuel pump). I don't for the life of me remember disconnecting a hose at that spot and can't find any reference in the service manuals.

So, the upper line of the main expansion tank connects to the upper rad line, the rear connector of the main tank seems to be an overflow line and is routed out to the bottom of the frame but I do not see any lines that connect to the bottom of the rear tank. Picture of tank attached.

 

I am going from memory here, but are you sure it's an actual nipple and not just a locating post that engages a hole to keep the bottom in place and then bolt the top?

 

Wait... you are talking about the (now) orange colored tank to the rear? That is the crankcase breather catch tank. It has a hose with a plug on the end that you drain every now and then.

 

The main tank has a nipple hat sits within the plastic frame but the rear one, "orange" is the one I am unsure of. It could be the previous owner left something off. But this afternoon, I wrestle with getting the freakin carbs back on. What a pain. Thanks for your input and if anything else comes to mind (where does the hose go?) please chime in.

 

I already answered your question. It is the Crankcase Breather Tank. A hose attaches to that nipple and is plugged for occasional draining. Here you can see the plug on my VF1000R that is a very similar set-up. Upper right corner under the yellow wires.



The hose is often semi-transparent, almost plastic. Probably has been missing for a while?

 

That look about right. So, without a plug line, I would likely leak coolant. I will rig one up.
Thanks.

 

For the 3rd time... NOT COOLANT!!!!

it is the crankcase breather catch tank. Every now and then you drain the goo that is in there. Jeesh.

 

Missed the "crankcase part". Ooops and thanks.