Random Vaccum Hose from Rear Carb
 

So when installing my shift light and gear indicator I decided to check my intake setup out and do a little snooping around the bike.

Upon inspection I found a random vacuum hose that comes off the rear carb that was lieing disconnected.

The line off the front carb goes to the petcock and I looked everywhere and cannot find where this vacuum line might need to be.

The correct routing is that line goes to the petcock and the front line should be plugged. ;)

And can be used for "syncing" the carbs when needed. I believe.

So i should switch them then huh

You don't really have to but that is how it is run stock.

Just run one to the petcock and plug the other (to use when you sync the carbs)

Gotcha....Same amount of vacuum from both i presume?

Well plugging that certainly changed the idle of the bike LOL

You will also notice A LOT less popping from the exhaust on deceleration with that plugged.