YICS repairs

[inanecathode]

Lol ok i was a bit worried  ;D (its like you said you were looking for a non flammable cleaner, so you used gasoline :o)

Thats odd it wont stick still. Can you tell if theres still a film between the pieces and it still seals or does it blow the joint out totally?

[tben]

Its just a small leak but enough to through everything off ::). I just pulled it apart and couldn't see any visible damage, I think it just didn't stick well enough this time. I'm about to JB weld it and I'll post how that works out.

[Tanno]

I'm surprised that some have had luck using silicone....because it stick to ANYTING dirty or oily. Proper prep is the best to use anything. I personally used 5min Epoxy. I've had issues with JB Weld combined with vibration and fuel (not with the YICS, but other projects). If it works for you then you won't have to do it again.

[Night Vision]

the first time I did the repair, I used JB weld.. did not last.
second time I used the gasket (Lucky's site) and permatex red high temp RTV... so far it's held so I did another like that also.... we'll see.

what you need is two of them in case one blows so you don't have down time.... they're not that expensive for the "crummy ones" (blistered chrome)....

I let them age at least a week.... not much air circulation in there

[JD Powell]

I cut mine apart with a hacksaw. Because it had developed a massive internal leak. Fixed with permatex cold weld. Think JB weld but with a 5 minute dry time vs. the 24 hrs JB requires. It is also much thicker in consistency which makes the setup and sealing easier.

[Rick G]

As far as I'm concerned , the only thing to seal a YIKS box with is Yamabond /Hondabond / 3 bond , the silver  sealer used  for centre cases. I used a  gasket on the first one I did , but it seemed over kill.  Three bond seals like there was no tomorrow , is fuel and oil proof and is not in the least vibration sensitive.

[tben]

My JB weld failed after a few hours of run time with a small internal leak. I'll be hunting down threebond next and give that a try.

[Cdnlouie]

Each man learns to master his own technique, but whatever you use, make sure the YICS is very clean.  Wash everything in something like "paint thinner," not the varsol base type, but the "tear the oils out of you skin" type (carb cleaner is not bad either), to strip the oils in the plastic.

Then if you use JB Weld or another epoxy, coat the inside with a layer down the sides of where the joint is going to be sealed to give you a better seal, as well as coat the outside with another thin layer all around the outside edge.  You can end up with a new layer about 1 inch wide around the inside and outside.  That was my approach and I've got 7 years and over 15,000 kms on this repair.

There are some pretty good techniques described here, but getting it right sometimes takes a bit of practice.

;D

[tben]

Well, I'm hopping 4th times the charm. ;D  The last two times I used nearly a whole can of brake cleaner to degrease the beast but I'll be searching my local hardware store for something else this time.

[Cdnlouie]

Brake cleaner is too mild, and I forgot to mention that you need to sand the surface to rough it up and give the epoxy or sealant something to bite into.  It's a good idea to sand around the inside and outside (scuff it up well) if you are using the epoxy and it ain't going anywhere.  Proper preparation is the key here.

Grit your teeth when you do it this time!  ;D

[Rick G]

I didn't remove any of the carbon inside the YIKS box. After cutting it apart , I used a sheet of 180 grit sand paper taped to a piece of Masonite  and sanded it 100 % level . I applied the 3 bond and screwed it shut , let it cure for 3 or 4 days  and reinstalled it. No trouble since  on any I've done.

[Cdnlouie]

You know Rick, that 3 bond is probably one of the best sealers. I'm with you on that one.  A darn good idea. Letting it cure is the plan.

;D

[hoverhead47]

Well, I'm hopping 4th times the charm. ;D  The last two times I used nearly a whole can of brake cleaner to degrease the beast but I'll be searching my local hardware store for something else this time.

Brake cleaner is absolutely useless at cleaning the inside of the YICS. I have just done it with both brake cleaner and carb cleaner on two YICS I have here. 
I cleaned the first one with carb cleaner and had dirty brown liquid still coming out after two of three rinses.
I used brake cleaner on my second YICS and had crustal clear cleaner drain out.  I then used some carb cleaner on it and had dirty brown liquid drain out. Unfortunately I've run out of carb cleaner  so was only able to do one chamber.
I've now opened it and it is very evident which side was cleaned with carb cleaner or brake cleaner.

[pinholenz]

In my experience (and quite a few other ROV members) the YICS is a waste of time on our XZ's. My bike is very happy without it.

We are still awaiting definitive evidence from a dynometer, with and without YICS, to see what, if any, difference it makes.

Personally I would save your time and your pennies by investing in some vacuum caps

[allstateguy]

if the YICS really does act as some type of "boost bottle", why not put empty CO2 cartridges on the ends of the hoses. Drill the ends out and polish them, and I think they'd be easy to mount - should just fit right in the hoses.

[Rikugun]

That might be a good solution and if it works let the forum in on your success. Several members have tried custom chambers from various materials i.e. copper tubing etc. Apparently the YICS has different volume chambers front and rear so I don't know how much effect that may have with matched CO2 cartidges.

I read your other post and my understanding is removing the leaky one helped the running issues but not completely. My guess is a non leaking YICS or DIY substitute (by itself0 will not fix the remaining fueling issues.

[allstateguy]

I hope to fix the remaining problems by ultrasonically cleaning and installing an 83 carb and going through all the diagnostic steps to eliminate vacuum leaks and synching them. The CO2 cartridge suggestion was just from an idea based on the lurking I've been doing for the last week or so. Reading about 10 kinds of glue on that two-piece plastic vacuum housing was getting a little old.

[Rikugun]

Yes many methods have been used to resurrect the YICS and some have proven to be temporary fixes. I removed mine early on as a diagnostic aid. I always thought I'd go back and try to repair it but there were always more pressing issues. I did eventually dig it out but upon close examination it's in pretty sad condition. By then the bike's various issues had been worked through and it was running pretty good so I never bothered to pursue the YICS any further.

Some claim noticeable fueling improvements with the YICS but I doubt I'll ever mess with the OEM unit. IF I ever did anything it would more likely be the approach you're taking with alternate materials to make a custom unit.

[turbosteve84]

OK, I went to THE engineering source on this "cylinder swirl" thing, non other than Kevin Cameron of Cycle World fame. I'm not kidding. (Not only couldn't I write like Kevin does below, I have a hard time understanding it!) Here's my question and his response. (I apologize for the snarkiness part of my question concerning the Vision)..

Kevin,

Back in the late '70s - early '80s it seemed like getting a so-called "swirl" of air/fuel into the combustion chamber was all the rage. Suzuki had its TSCC (Twin Swirl Combustion Chamber), and not to be outdone Yamaha's system had this unfortunate acronym: Y.I.C.S. (Yamaha Induction Control System). The purpose, as advertised, was to achieve more efficient burning resulting in (trumpets please) "more power and greater fuel economy!"

As memory serves the Yamaha Vision version of Y.I.C.S. was a cheap plastic dual chamber connected by hoses to the intake side of the cylinder heads. Kind of like little Johnny's ninth grade science project.

To my knowledge these systems went the way of the anti-dive fork. Where these just marketing ploys or was there solid science lurking somewhere?

Thank you,
Steve Klose


Steve,

Whatever systems those two companies developed in that period, they did not save Suzuki from their decision to shorten the GSX-R750's stroke to 44.7-mm for 1988, with resulting reduced performance, as attested by their return to the previous longer 48.7 stroke. Yamaha, too, had combustion trouble, for the production FZR750 needed a tremendous 45-degrees BTDC ignition timing to burn its wide but vertically very thin 5-valve combustion chamber (I still have the rubber cast). The longer combustion takes, the more heat is lost from the hot combustion gas to the surrounding metal surfaces, and the more torque suffers.

This puzzled me, because Keith Duckworth had shown the world how to make short stroke, large-bore engines burn rapidly and efficiently, through intake-generated charge tumble. Duckworth's revolutionary DFV F1 engine of 1967 fired at 27-degrees BTDC.

What I must assume is that only the appearance of Duckworth's new paradigm (a steep intake downdraft angle) was applied to Japanese sports engines of the 1980s, but without achieving the effect.

When I asked Claudio Domenicali at Ducati about this, he replied, "Obviously I cannot speak for the Japanese case, but here, we have specific tests by which we develop the necessary degree of combustion speed."

He went on to say that they had used the same basic tool pioneered by Harry Ricardo in his 1920s turbulence research - an in-cylinder anemometer (today this may be supplemented or replaced by CFD ((Computational Fluid Dynamics? -Steve)) ). By varying the intake downdraft angle and intake velocity, the charge entering the cylinder could be made to flow across the head, down the far cylinder wall, back across the piston crown, and up the intake cylinder wall. As the piston rose on compression, this "tumble" pattern of rotation would first preserve the energy of intake air motion, then break up into a multitude of flame-speeding eddies as the piston neared TDC.

Japanese manufacturers soon rectified their mistakes to become masters, and their early approaches to the combustion problem went into the archives.

KC

I'm concluding from this that either, A) the YICS system is rubbish, or B) it was fine for the engines Yamaha was building in the '70s and '80s, but useless science today. Now, take your side and make your point.

[Rikugun]

Well, I guess I have to admit to being slightly disappointed......  I saw all that reading ahead of me and thought "Certainly, there must be an answer by the end. " Alas, only more questions!   :D

I have to admire Claudio Domenicali's answer though "...but here, we have specific tests by which we develop the necessary degree of combustion speed."   Is it me or does add nothing to the discussion!?

Interesting perspective and ultimately I could be satisfied with "I don't know."