YICS NO MORE!

[zore]

So I repaired my yics box in the beginning of spring using epoxy.  It held pretty good up until this morning.  It went from a perfectly good running motorcycle to a pile of poop over night.  I shouldn't say it didnt' run well, it just wouldn't idle.  The box leaks internally so I think I'm going to leave it off.

What I did notice while taking a look at things is that I had 135 air jets in it.  I removed those and put 130's in it.  I also jetted up the carb from a 125 rear to 127.5 rear.  I did some mixture adjustment and it seems to run pretty good now.  YICS is dead to me.

[QBS]

Would someone please describe the sypmtoms of a failed YICs to me?  My '83 with approx. 85k miles has never (to my knowledge) had a YICs related problem.  I've never done any repair to the YICs unit.  Now the bike has just recently begun to die while idling.  It doesn't die suddenly like it's loosing ignition.  But rather, kinda misses a few times and then fades away.  Holding the idle up around 1500 to 1700  with the throttle will keep it running, but that just masks the real problem, whatever it may be.

Otherwise, it romps and stomps.  Starts very good cold.  Can be a little reluctant to start hot, but it always does eventually.

[Sable]

Can't give you symptoms for a failed YICS... when mine went I had a lot of other problems with the V, dirty carbs, exhaust leak, carbs not sinked... etc.
It's only one bolt and two hoses to pull off the YICS... then just get some extra hose and a bucket of water and do the test on Lucky's site. Mine had both an internal and external leak.

~Sable

[glennw]

I just pulled my YICS and capped the holes... I would say the bike idles much better and runs the same in any rpm range... as it did before.
My .02...
GlennW

[Tiger]

I just pulled my YICS and capped the holes... I would say the bike idles much better and runs the same in any rpm range... as it did before.
My .02...
GlennW

:).......DITTO.... 8)

[h2olawyer]

I'll keep mine on.  With it sealed (internally & externally) I have good, steady idle & it seems to have a little better acceleration than when I've had it off.  The way I have it sealed, it will be easy to repair when it leaks again.

A leaky YICS has several symptoms but the only one I can recall offhand is the 'hunting' idle.  When mine was leaking, the idle would fluctuate between 1,000 & about 2500 RPMs.

H₂O

[zore]

My new way of looking at things on that bike.  If it can break and isn't required to get me from point a to point b, it's coming off.

[visionless]

I took my YICS off and plugged the lines, bike runs great.
      Chris

[Superfly]

I did see a dyno test somewhere that showed the difference between running one with the YICS & one without the YICS, and there was a slight difference (not too much) at the peak of the powerband.  I have been trying to keep that darn thing seald for a while now, but I always keep breaking the seal.  As soon as the idle gets a little erratic, I know it broke a seal again.

[Brian_Matthewson]

My new way of looking at things on that bike.  If it can break and isn't required to get me from point a to point b, it's coming off.

My sentiments exactly!! That's why I also removed the fuel pump...gravity is more reliable!

Brian

[VisionaryDan]

Guys not to beat a dead horse but I have both my bikes fitted with copper YICS chambers and they both run great. I can see no way for these to ever fail. I have been running with them for over a year now without any ill effects. I had posted pics and dimensions but I don't believe they are still viewable.

I can definately tell the difference between YICS and no YICS. As Superfly has said the bike runs stronger when in the powerband. 

I was able to wire tie them to the frame. I used 1" copper tubing T fitting with a 1/2 pipe from the center. With the 1" end caps this came out to a perfect length 5" to give me a 70cc chamber.? I then soldered a 1/8 pipe threaded adapter into the 1/2 inlet and screwed in a 5/16 hose end. I pressure tested both chambers and everything was sealed tight. Just keep the hoses as short as possible otherwise you may get a backfire problem after the bike sits at an idle for extended periods.

Here are a couple of the pics

Dan

[zore]

Even when my yics box was sealed and the bike was running well, I could tell no difference in power.  The only difference I feel is when the yics starts to leak and my blood presure rises.  I then pull it off with all hoses attached and throw it as hard as I can against the closes concrete wall.  Then i stomp on it until my foot hurts.  I would really need to see some dyno figures of it with it on and off for me to believe it does anything.

[tremalzo]

I took the YICS of too. For about 2 years I just had a hose between the holes. This spring I capped the holes to sync the carbs and left the caps on because it idles better. No difference in riding either with the hose or caps.

Frans

[d0n]

Why did they add that yics anyway?

While I'm at it... why did they make the petcock so complicated with the vacuum setup? Wouldn't a regular petcock have been much more reliable?

[h2olawyer]

The YICS came about early in the days of concerns over emissions & fuel economy.  They were trying to squeeze out all the power they could while using less fuel & making a cleaner burning engine.  While YICS has minor effects, it was a cost effective way to experiment.

The petcock is vacuum actuated so you don't need to remember to turn it on & off every time you want to ride.  Fuel won't flow (or is not supposed to) without vacuum unless it is set to PRI(me).  Just makes it less hassle to go riding & not worry about the bike running out of fuel a little ways down the block - or not worrying about filling the crankcase with fuel if you forget to turn the petcock off.

H₂O

[Extent]

I would really need to see some dyno figures of it with it on and off for me to believe it does anything.

I actually remembered to save a copy of those charts, you can see a dyno comparison here
http://rovmedia.dyndns.org/forum/download.php?id=669

I mostly notice the YICS doing cold starts and when using the choke.  I'm still trying to finish my replacement, but progress has been slow, especially recently.

[Superfly]

I would never have remembered to do that!

[YellowJacket!]

I noticed that my V was running a bit rough fo rthe last few weeks but pretty much ignored it.  I thought maybe it just needed a few more adjustments to tune up after Lucky and I synced the carbs - remember, they were WAY out of sync. But...I'm sometimes a procrastinator so I let it go.  I had some time today so I pulled my YICS off and dunked it in a bucket of water and blew through it.  It looked like a stinkin fish tank bubbler.  Leaks everywhere.
This was the YICS that I repaired with Epoxy and heavy duty JB Weld.  Both the epoxy and the JB Weld gave out.
I capped off the YICS ports on the motor and started her back up, adjusted the idle and took her for a ride. MUCH MUCH better!
I still think my bike ran better when the YICS was working.  I could definitely tell a difference when it was not.  I'll probably leave it off for the rest of the season as I'll be puling the motor this winter to polish it up.

david

[Extent]

Oops, forgot to turn on guest downloads for that forum.  Sorry to everyone who had to sign up to see the picture.  I fixed it so you don't have to anymore.

[zore]

Going by the dyno, you would probably get equal performance increase from the weight saved by yanking it off.  Don't know but given how poorly the are constructed, it's not worth the hassel.

Would have been interesting to see how it would have been had the jetting been played wiht for non yics.  My bike runs 100x better now than it ever has.  I may try to do the copper yics  and see how that works.