vacuum petcock

[pIatipus]

Just picked up a 1978 xs400, & the petcock's vacuum line isn't hooked into anything. So far, I've been told it needs to go into one of the carbs. The left carb has a vacuum cap, the right has blue tape. High tech. Anyway, does anyone know if it goes to the left or right carb?

 

[BBS360]

Stock would be the left carb boot. Shouldn't make any difference either way.
Mine had been swapped at some point before I got it. The tube routing almost seems to fit better when run to the right boot.

 

[xschris]

The right boot is the stock location.

 

[BBS360]

You're destined to correct that every time.
I had read here that left was stock but double-checking that thread again, you had corrected them too.

The parts fiche and Haynes manuals show the right vacuum barb capped, implying the left one is to be used. Neither actually say which to use though.

 

[xschris]

Using the right one is much easier. All the bikes that I have seen that are still stock and pics of old ads show the right one with the hose on it.

 

[buztabuzt]

Looking to confirm where the vacuum hose is supposed to be installed. Based on this thread, I presume it can be attached on these carb boots under the black plug if I take a plyers to pull it off? I ordered replacement boots, these look like hell. I honestly didn't realize it was vacuum hose, thought it was a breather tube. Dope!

 

[xschris]

View attachment 33178 Yes that's where you attach the vacuum hose for the oem petcock. It's a good idea to use ethanol resistant bike hose for the bike as it will flex better than automotive type hose. I use motion pro with a in-line filter for my oem petcocks.
View attachment 33178