Yics Box

[Rob_OS23]

Hello, I am having trouble with a leaky YICS box.  I have a spare that I am pretty sure is leak free, but I was wondering...
Has anyone ever thought about having a YICS box reproduced using metal?
I know a guy who can work wonders on a hunk of metal, and I'm sure if enough of us wanted them, he might do it as a side job for the right price.
Is there any reasons why this wouldn't be a good idea?

Hey, I'm an idea guy, I don't know all the reasons why my ideas won't work! lol

[Lucky]

It has been discussed before, not sure if the poster tried it or not.  

How the YICS works:
 the YICS depends on cylinder vaccume & intake "pressure' to 'operate'.   it's job is to inject a swirl of fuel/air mixture into the cylinder to promote better mixing in the cylinder.  

to do this, when the intake valve opens, and mixture is being drawn in, vacuume puts the YICS under negative pressure. when the intake valve closes the YICS sucks in some mixture.

when the intake valve opens again, that mixture is drawn out & into the cylinder. (if the valves need adjustment, the YICS won't work efficently)

Here's why I think a metal YICS wouldn't work: (I could be wrong)
 For the YICS to work I believe it needs to have some flexability in it's walls inorder to "pulse"  if you look at it, the walls of the YICS are pretty thick for a piece of plastic.  I think if you wanted to acieve the same effect with metal, it would need to be tin-can-thin, and with the stresses & caustic enviroment it is in, I doubt it would last too long.  poss if it were made of welded stainless steel (coated with POR-15 inside?) that might work, but if I were Yamaha, I would have opted for the cheaper plastic.

This is my opinion, & I could be wrong.  I'll voulnteer to be the test pig for a stainless steel unit if you build one though, lol!

-Lucky

[Rob_OS23]

Yeah, it might be a lot of work for nothing....

I don't quite understand why the walls need to flex though, is it because you think that it would rip weld joints apart?

Here's another side question about the YICS.
Last summer while cleaning the carbs, I noticed that the hoses coming off the YICS were in horrible condition.  I looked all over town, and could not find any hose that had the same diameter inside the hose as the ones that were on it originally.  I ended up going to Ideal Supply, and getting vacuum hose.  It was smaller inside then the original hoses, and I had to stretch it to get it over the (I don't know what you call them) on the Yics box.  Would this effect performance?  If so, does anyone know exactly what kind and size of tubing I need to get, and what Canadian store might carry it?
Thanks

[Lucky]

I think the YICS box needs to flex inorder to allow it to operate. the amount of flex is probably imperceptable visually, but you probably could feel it.  imagine trying to create a vacuume in a solid block of metal or plastic, then imagine trying to do that with something that has walls with a little flex to it.

I don't think it would pull the weld seams apart, rather that it would fatigue the metal.  lots of old Fords use what look like an old Folgers coffee can to hold vacuume for the AC system, so poss it's not that far fetched an idea.  the pulses/vacuume for our use are more severe though.

I think a brushed stainless steel YICS would look cool.

[jasonm.]

The YICS is used to correct for volume flow. You ask...what??? The carbs are close enough and the cams are of such a design that for optimum atomization intake mixture the YICS is needed. As far as flexibility of the box...It is plastic for light weight and the vacuum is only high on the box when the throttle is closed. The YICS box can be easily fixed. First you remove the cover and all screws. Then set it on the floor, maybe on a block of wood. Then hit it with a hammer on one of it's corners. It will pop apart. Then using JB Kwik Weld cement it back together. There are 2 chambers in the box. They have to be sealer from each other. I have repaired 2 or 3 like this.

[Lucky]

make sure the mounting bolt tab (that bolts to the carb) isn't down on the block of wood, it will break off (I did this, Duh for me!)

[Rob_OS23]

I have seen those cans you are talking about Lucky, in a friends 80's lincoln.  We compared it to an apple juice can, and it was EXACTLY the same, down to the position of the lines around the can and everything(height, diameter etc.), except that it had been painted flat black.

I will attempt to repair my old YICS box the way you mentioned.  I had heard that you had to hacksaw it down the middle.  Hopefully it pops open as easy as you say.
Thanks for the help.

[Lucky]

The 2 i've popped open didn't open as easily as Jasons did, but they did open.  it took some good wacks with a hammer, and a little prying with a flat screwdriver.  try this first before resorting to a band saw (not a hack saw)

--Lucky

[h2olawyer]

Having experienced the bandsaw method personally, I recommend the hammer route too.  While I managed to get it all back together & working for over 2500 miles so far,  getting all the edges on both halves smooth, even, true & flat took quite a while.

I like the idea of a brushed stainless YICS, but it might be easier just to fabricate the cover, replacing the chrome plastic one Yamaha made.

H2O

[Superfly]

I was at the local bike junkyard this weekend, and picked up a clutch lever assembly off of a Turbo, and I saw what I think is a Virago in there, (the same type of wheels that are on ebay right now) & it had a YICS box on it, only it was not the soft plastic we are used to on the Vision.  It is a very hard white plastic that did not flex at all.  I checked it for leaks, and it was perfectly in tact.  I went home & put in on my re-built V, and it works good.  I can not tell the ultimate proformance of it yet because I do not have the bike running exactly right yet (But good enough to get it registered at the DMV!!)

[CH3NO2]

Rob
   Are you reading my mind? I built this.... javascript:OpenWindow('http://mysite.verizon.net/vzeeet5n/') in November. It's too cold in Massachusetts to try it out now, But I will let everyone know how it works in the Spring. It is Billet aluminum. There are actually two seperate chambers that can be removed seperately. I wonder what the result of changing the volume of the YICS would be? I am considering making 2 more. One with more volume and one with less. Just to try it out. I don't think that it needs to flex.

Al

[Walt_M.]

Good looking job! Don't know why it shouldn't work.

[Rob_OS23]

That is pretty cool!
h2olawyer, I was not thinking about the looks, I wanted it to still be under the original cover for the YICS box.  I was more thinking of durability.  My one that I used last year(the leaky one)  looks fine, but leaks like a siv.  However, the one that I believe is ok, looks like it has many fine cracks on the outside, and I just wonder how long it will last....thought metal might last for good.
CH3NO2, like the box!  Do you have any shots of the box opened up?  What do you suppose changing the volume sizes of the chambers will do?  I really am not gifted mechanically, or with the understanding of these things, so I am just wondering what that would mean as far as performance?
Really like the work so far.

[Lucky]

Hey Al, we're neighbors (i'm in RI) where-abouts in Taxacusetts are you?

[h2olawyer]

h2olawyer, I was not thinking about the looks

Actually, I was following up on Lucky's comment:

I think a brushed stainless steel YICS would look cool

You won't get any argument from me on the increased durability of metal in most situations.  The one Al (CH3NO2) made looks teriffic & if the box doesn't need to "breathe", it should work great & outlast the bike.

H2O

[jone]

hey Al , i was planing to do my YICS this winter,and billet is a
good idea.I might try that it would be easyer than cast one.
Is there a reason why those tube connectors are at allmost top of the box,plastic ones connectors are at the bottom.
You might end up a box with full of condensed gas in it?
Jone

[Ron_McCoy]

I replaced my YICS box with a pair of  aluminum cylinders
I fabricated and machined from 6061 T6 aluminum tubing   and roundstock.  I measured the volume of the YICS chambers and duplicated that.  I can tell no difference switching back and forth from them to the original set up. The advantage is that I don't expect these to develope leaks since they are one piece and I didn't care for the cheap chrome plastic look of the original.

[CH3NO2]

Lucky
   I am located in Athol, MA I used to be closer to you in Leominster, MA. I am probably about 1 hour and 15 minutes from the R.I. border. I am the guy who sent you the free guages a year or so ago. Maybe we could hook up for a ride sometime. Mount Wachusett is a nice ride in my area.

Jone
   There is no real reason why I put the connectors where they are, but you have a good point about fuel bulding up in it. If it does I will move the nipples to the bottom.

Al

[Mike Kurvink]

Hi
I've had my XZ550 for about a year now and have looked at this site off and on for a while in order to keep it running.
A most valuable resource for all XZ owners. Thankyou ROV members, from those of us having a peak from afar.
I was lucky and got a really well looked after bike but still had to do the usual electrical fixs and carb cleaning etc.
My YICS was fitted for looks only, not connected. The cylinder YICS connections are simply linked directly together with vacuum hose. I have pinched the hose close to tune the carbs and it drops a lot of revs from its normal idle. It runs pretty well linked like this, but does have the bog/stumble at times. Still have to balance the carbs properly.
Has any body else tried linking the YICS.

I also have an IT465 which has a big YIES cannister (same thing as YICS) which I had to replace with a stainless tube version after the original plastic one got broken. It gives much better air flow through the carb with it on, for smoother running and less peaky power. I figure my XZ link is doing the same thing as the YICS.

[silicon_toad2000]

My YICS hoses are hooked together, I have not taken them apart to see if they are sealed from each other or not. Thinkning about it, If the YICS hoses are joined together, then you have, in effect, a YICS chamber of infinite volume.
I can't see a downside to this, but the Yamaha engineers must have used the chamber for some reason. The only thing I can think of is that when the valve opens up and the piston travels down the YICS creates turbulance in the port by injecting air/fuel as pressure drops, and then as the piston slows down and the air pressure increases relative to the YICS chamber it would suck air in creating more turbulence. With the hoses connected, the YICS port would constantly be injecting air/fuel rather than 'blowing and sucking'.
Has anyone seen a dyno print of a with and with YICS situation?
Sorry about the waffle, just my brain clunking over (maybe I need a YICS)