What was the previous owner doing?

[DarthLoser]

My bike was shuddering / jumping at low and constant speeds.  I found a random vacuum line lying around the engine, posted a forum question about it, received a prompt reply and quickly fixed it.

You can check out that previous post here

Now I'm wondering what the previous owner was trying to do.  Maybe it'll lead me to other things that need to be fixed...

     BEFORE:




     AFTER:



     THIS IS WHAT YAMAHA SAYS  <CLICK HERE>

     Any help would be appreciated!

[Arnie]

No idea what the PO was trying to do. 
WAG might be to equalize the manifold vacuum by jumpering the taps, but ?
In any case you have it back to normal now.

How is it for smoothness now?  Did you sync the carbs too ?

Arnie

[Goetz]

Check your countershaft sprocket

[yosemite]

At a first guess the po tried to balance his carbs,and either lost or damaged his blanking caps so he used a couple of lengths of fuel pipe  to stop air getting sucked in through the spigots

or possibly he had had a twin carb seventies bonnie or other trumpet,some of these had a couple of spigots on the bottom of the inlet manifolds, with a similair link pipe called a "balance pipe" by triumph to the setup in your "before " photo and maybe he thought that it was an easy way to balance a pair of carbs.
Either way it would suggest that he had carb or a tickover problem he had tried to cure
 

yosemite

[andyb]

If the carbs are balanced, it's okay to connect the spigots to each other.  One of my Kaw's came from the factory that way.

Having the boost line open to air is unlikely to improve performance though.


Assuming someone was trying to synch or something involving those ports, the obvious question now would be if you've thrown a synch at it yet?  Unbalanced carbs can give all sorts of weird troubles that make troubleshooting other things harder than it needs to be.

[FJmonkey]

Dude, in early 2013 you can bring your FJ to my house and get your carbs synced. I have a borrowed sync tool (thanks Dan) and as long as I have it, it needs to do some good. If your FJ runs then get the beast to my house and lets get er' done... The Monkey has spoken.... That is all.....

[Goetz]

I recently had the same problem, found that the #3 carb nipple had shot off and was lying on the starter? cover. doh.