YICS and the choke

[Extent]

ok so I've been dealing w/ the 4-5k stumble and I was sure I had to dip the carbs.  I synced the carbs, lowered the idle to the haynes spec (1.5k down to 1.3k) and filled a tank w/ the chemtool gas additive carb cleaner thing, I figured why not, while I'm waiting to get rebuild kits and the dip (which my autozone is out of right now)  So for the last two days when the bike is not completely warmed up it idles really low, down about to 800, and has a tendency to stall out at stops.  At full choke it runs up at 3k.

On whim I check the YICS and I'll be, it's leaking internally and externally.  So I pull it off and cap the ports and run the bike around a little bit and the stumble actually seems to be completely gone, which I wasn't expecting, and the idle dropped down to 1k (which I readjusted back up).  However the bike hates the choke now.  I just start it with no choke and pump the throttle once or twice, but when I bring the choke up it kills the engine completely.  If i put the (now only leaking internally) YICS back on the choke works just like it did before, starting the bike cold easy and reving it high.

I'm going to repair the rest of the YICS in the next couple days and put it all back on and see what happens, but is this choke behaviour normal for a YICSless setup?  It basically isn't necisary at all anymore.  Thoughts? Comments?

[nvdranger]

i took off the yikes as well and have the same results.  i built a gasket for the yikes but the bike doesn't seem to run as well with it.  I water tested the yics, plugged one up and hook up the other to the yics..no leak internally.  I plugged them and forgot about it.

Ken

[Glyn Pickering]

What is the difference between internal and external leaking on the Yikes? Can a bike be made to run without it - like other v twins??

Cheers

Glyn

[Lucky]

you can see the inside of the YICS here:
http://www.xz550.com/YICS.html
as you can see, since the YICS connects both cylinders, if it leaks around the outside, it creates a big vacuume leak, leaning out the mixture.  if it leaks at the center divider, it effectivley joins the two intakes. (hunting idle is one symptom) if bit leaks both ways the bike will be hard to start, and symptoms can vary depending how much it leaks where.
--Lucky

[Glyn Pickering]

I'm going to have a go at making my own YICS - actually it will be PICS (Pickering Induction Control System).

See other post.