YICS

[mastergunny]

Just what does this do? I pulled the little plastic triangle shapped do dad, and am preparing to ship my carbs to Rick for overhaul. Just curious as to how it works and are they needed?

[acee125]

I believe it supplys vacuum to the carbs for initial throttle openings...?

[YellowJacket!]

Nope. It is pressurized during the exhaust cycle and releases the pressure during the intake and helps thefuel burn better.

David

[mastergunny]

How about the second question in my original post? ???

[h2olawyer]

It is not a 'necessary' part.  However, I notice a better idle & low end performance when mine is attached & not leaking.

That said, most of us here recommend disconnecting it & plugging off the ports on the heads until you have the carbs well tuned & synched.  It removes one variable when getting the bike running smoothly.  Also, it makes checking the synch much easier if the YICS is plugged off.

After you are running smoothly, you can test the YICS box for leaks (which are VERY likely), repair the unit & install.  A little final carb tuning and you should be good to go.  I found my V will idle about 1200 RPM higher with a functioning YICS installed, so I need to turn the idle down a bit.

H₂O

[Rick G]

You should certainly cap off the YIKS ports when syncing the carbs . I was taught to sync at 2500 rpm , not at idle.

[jasonm.]

H2O is correct. I have sync'd both with and w/o the YICS...no difference noted on my carb sync tool other than it idles lower w/o YICS. I also sync @2500 or higher. MAKES FOR SMOOTHER running.