Carb Sync YICS Tool

I found this and thought it was interesting. It is a direct cut and paste.

Comments please.



SUPPLEMENT

1984 AND LATER SERVICE INFORMATION

The following supplement provides additional information
for servicing these 1984 and later models:
a. 1984 FJ600L and LC.
b. 1985 FJ600N and NC.
c. 1984 XJ550 (U.K.).
d. 1984-1987 and 1989-1992 XJ600.
Other service procedures remain the same as described
in the basic book, Chapters One through
Eleven...........

Carburetor Synchronization

The Yamaha Induction Control System (YICS)
used on 1983 and earlier models is not used on 1984
and later models. During carburetor synchronization
procedures described in Chapter Three of the main
book, the YICS shutoff tool is not required.

 

They must of figured out it was a great big pain in the keyster!

 

Reading this forum as a resource for fixing the bike I am working on, I have seen the carb sync'n argued both ways, with and without the YICS tool.

Not knowing the answer my self I found this interesting.

I subscribe to the yes theory on the YICS tool, now I am wondering.

 

You have to block the passages somehow to do a proper carb sync. I've seen many an alternative on this site, all of which probably work just fine. Me, I prefer the actual article and have a YICS tool I purchased from chacal.

 

I read it this way - since this is a sup for 1984 and newer they are saying those bikes don't have YICS so you don't need the tool for them. It is being stated as an exception to the statement about Chapters 1 through 11 procedures being valid

 

The note implies that the YICS was no longer used? I dunno about the other models but on my 1984 XJ550, the YICS is alive and well (lettering and ports for the tool are there). I tried to synch with and without the tool and I don't get the same reading using synch sticks. Much better with the tool.

 

try it both ways, form your own opinion
only takes a few minutes once your setup, ya can't hurt anything
thats the only way to know for sure, what works best for you on your bike
the main thing is to sync them somehow, either way is better than a bench sync

 

Bill, I read it as 84 and LATER.

 

Runway, unless it an error that's what I read. I was hoping to get clarification from some of the more knowledgeable.

 

Polock, I did it with the YICS tool, after the pilot screws are set I will go back and check it both ways.

I will say this, there was a noticeable improvement after syncing a 1985 XJ550 (84 and LATER) with the YICS tool.

 

Hmm I see your point - OK I'm confused. I'm sticking to sync with the tool - I already paid the money

This will be an interesting debate.

 

Bill, I was wondering if the early carbs were not vacuume operated, perhaps the CV's don't require the YICS tool for the sync.

I stumbled across this:

Title Control of carburetor-supplied induction system

Creator/Author Matsumoto, H.

Publication Date 1984 May 01

OSTI Identifier OSTI ID: 6326979

Report Number(s) US 4445473

Resource Type Patent

Resource Relation Pat. File: Priority date 13 Nov 1979, Japan; PAT-APPL-93915

Subject 330100 -- Internal Combustion Engines; ;CARBURETORS-- CONTROL SYSTEMS;CONTROL SYSTEMS-- DESIGN; COMBUSTION CHAMBERS;CYLINDERS;FUEL-AIR RATIO;INTERNAL COMBUSTION ENGINES;TURBULENT FLOW;VALVES;VORTEX FLOW
Related Subject CONTROL EQUIPMENT;ENGINES;EQUIPMENT;FLOW REGULATORS;FLUID FLOW;FUEL SYSTEMS;HEAT ENGINES

Description/Abstract A control for carburetor-supplied induction systems for internal combustion engines.^The engine includes a carburetor and a principal induction passage leading to an intake valve and thence to a combustion chamber.^A principal throttle in the carburetor controls the supply of air/fuel mixture to the principal induction passage as a function of throttle setting and engine demand.^This invention includes an auxiliary throttle valve in the principal induction passage between the principal throttle and the intake valve, and an auxiliary induction passage extending from a point in the principal induction passage between the two throttles to a point adjacent to the intake valve where its discharge will, when the intake valve is open, enter the combustion chamber in such a way as to cause swirl and/or turbulence.^The auxiliary throttle is closed at light loads so that the bulk of the intake charge is delivered to the combustion chamber through the auxiliary induction passage.^The invention contemplates the use of one carburetor for more than one cylinder, and also a number of carburetors equal in number to the number of the cylinders.
Country of Publication United States

Language English

Format Pages: v

Rights Yamaha Hatsumoto Kabushiki Kaisha (Japan)

 

Check this out, it's not on my bike. It could be for snow mobiles for all I know.

http://www.xz550.com/YICS.html

 

Non CV carbs used a slide attached to the throttle to control the opening and thereby the fuel/air mix. Our carbs are CV (butterfly opens - causes pressure differential (vacuum) and lifts the pistons allowing more fuel). So yes earlier carbs did not employee vacuum.

But I'm not clear on your comment: perhaps the CV's don't require the YICS tool for the sync

 

1st let me state that this is my 1st experience with the XJ series bikes, so I know little about the specifics. I am still trying to learn if what I am working with are stock un-molested parts and systems.

I do not know when the CV carbs went into use on the XJ, perhaps they always did. I was just thinking out loud that perhaps because of the shared vacuum that bikes with CV's did not require the use of the YICS tool. Were the carbs non vacuum prior to 1984 on some models?

When I came across the link showing the YICS as a seperate chamber, it got me thinking. The discription makes it sound like the box is plumbed to the vacuum ports adding additional air to the intake charge down stream.

My bike draws air through the carb only, the vacuum ports on the intake manifold are sealed, I dont see how they will create aditional swirl in the intake charge.

 

All XJ's and most (if not all) XS and XV series use CV (constant velocity) carbs, either Mikuni or Hitachi brand. Some people even use newer Keihin models (with some major tweaking).

Earlier XJ's that did not have YICS, still had CV carbs. YICS was added later as a fuel saving/marketing device.

If I understand it correctly, YICS has a two-fold purpose: One is to help equalize uneven vacuum pressure in a separate chamber, another is to swirl the fuel-air mix so that a leaner mixture can be used to create the same amount of power as a non-YICS motor.

You have to use the YICS tool to "disable" the YICS chamber, to help during the sync process. Honestly, I can hardly tell the difference whether I use it or not, but then again, I don't have access to a dyno... :mrgreen:

 

We don't have an auxillary throttle, as specified in the above abstraction, which seems to be the patent for YICS. The aux. throttle would be necessary in a 1 carb or shared plenum set-up because YICS requires a pressure difference from port to port in order for air/fuel to flow thru a relatively tiny drilled passage, that induces a swirl into the combustion chamber on the intake stroke.

It seems that Yamaha included the auxillary throttle just to cover all applications of YICS.

Also, all XJ's have CV carbs, except the fuel injected models that we're so jealous of.

 

My 1981 XJ750RH SECA is a YICS bike. Syncing was a pain in the butt without the YICS tool, but I got it reasonably close. And my carbs are CV, btw. Pretty sure all of the XJ's use CV carbs.

 

Thanks everyone for the info about the CV's.

Now what about the link I posted showing the "Box" ? Is that supposed to be on this 1985 XJ550?

If so, it's not, and because it's not what's the down side if any?

My vacuum taps 1,3,&4 are capped, 2 is attached to the petcock.

How is the YICS principle working with the taps capped off. Where does/would the aditional air come from?

 

Just for trhe sake of it...
are you looking at the nipples on top of the intake boot,
or are you looking at the YICS passage under the intake books, cast into the head.

I say, If you dont like the passage SEAL IT UP....
I place a blocking tool inside and the bike runs inefficently(not performance grade)
removed- I hit the 1st gear super/duper/fired up button and the front end wheelies a bit.
I am sure you can run without the yics, but rejetting and float levels and general tuning might be required

 

switch, FYI syncing WITH the YICS tool is also a PIA.

I did to one gauge rickOmatic method.

 

Assfault never said I don't like it. I am just trying to get an answer to the question. YICS tool yes or no seems to be a point of debate.

I was refering to the nipples on top of the intake manifold, that's what I tapped into to sync.

 

The way I understand the YICS system, it doesnt pull additional air, at all. The YICS passages connect all 4 intakes so that the vacuum levels are somewhat balanced between them all, is what I was under the impression was going on.

 

Sorry I was referring to those who think the system is just a marketing gimmick.
I think it does indeed help and no one else has yet to PROVE that it DOES NOT WORK.
When I see numbers I will conceed my position.

This position is of course referring the point that the YICS helps the engine run better NOT that the tool is required.
I personally use the tool and the bike runs much better after a sync w/ the tool.

 

I used the tool on "mine". It made a noticeable improvement in the mid and high circuit. I still have a slight stumble from 1500-2500 but it gets better each time I tweek the pilot.

The bike is very cold natured, will the cold rideability get better after final tweeks are set, or is this just the nature of the beast?

I am considering a colortune, but am hesitent to spend the money, I typically use A/F meters with O2 sensors but can't with this bike.

I am still curious about the YICS "Box".

 

Sounds like the starter jet wells might need a cleaning.
and while your in there clean it out completely

 

Wow go to lunch and look what happens - Better answers than I could give. Way to go gang. I knew this would be an interesting thread.

Let me make sure everyone understands I'm not representing myself as an expert, but I am old and have owned/maintained several bikes including the older slide type carbs. So I take my best shot at your questions and am enjoying the conversation.

The box article is puzzling I think the explanation above by Stereomind is as I understand it to work

 

1) although the Yammy manual didn't specify using a colortune, that may be because it specified using a gas spectrum analyzer for fine-tuing, which of course most of don't have access to----so a colortune is the next best thing (perhaps/maybe/probably better than "by ear", at least for most people). Perhaps the colortune plug wasn't even readily available (or known to Yamaha) at that point in history. Or maybe an OEM like Yamaha felt it had to rely on only the absolutely most precise method of tuning generally available to them---pesky federal regs and all that---and therefore determined that the absolutely best way was an analysis of exhaust gas products (which is probably true, since Yamaha was specifying a method of tuning for Lowest Emissions within an acceptable range of performance, rather than for Best Performance within an unknown range of emissions---although I realize there is a certain overlap in those goals).

2) I believe that the YICS tool is useful for getting a better "fine-tune". It allows the isolation of each cylinder/carb unit from all the others, therefore allowing a precise setting of each unit individually, without the influence of other carb/cylinder units to "balance" the weaker or stronger units. Note that the purpose of the YICS system is NOT to "balance" the carb systems, although it supposedly does function in that manner anyway, whether by design or not.

Ideally, we want each cylinder/carb unit to be both equal to all the others in term of efficiency and effectiveness RELATIVE TO THE OTHERS. This allows each unit to pull an equal amount of weight in the engine---important for both engine longevity, efficiency, and performance (both output performance and emissions performance).

Doing so means "tuning down" certain units to match the "lowest common denominator" carb/cylinder unit.

3) Now that each unit is working equally hard, the removal and "balance" achieved by the YICS passage allows for operating variations to be better controlled than by NOT HAVING THE BALANCING EFFECT OF THAT PASSAGE. Under the variety of operating conditions, situations, and loads that an engine experiences...and thus what each INDIVIDUAL cylinder "sees"....it is useful to minimize the effect of such variances on the overall engine, and thus one of the effects of the YICS chamber.

4) Interestingly, Yamaha states only the following about the YCIS system in their marketing materials. Note that there is no reference to emissions or to carb synchronization, etc......it's merely a performance enhancement feature that has nothing to do with better performance via a "balanced" intake system:

"...the Yamaha Induction Control System (YICS) adds power in the low to mid-range and delivers about a 10-percent increase in fuel efficiency. YICS is a secondary port cast into the cylinder head, linking the main induction tracts. It brings the secondary charge into the main tract at an angle so that it mixes with the main flow of fuel and the mixture is swirled completely around the combustion chamber, thus resulting in more complete cylinder filling, which leads to more power and less fuel consumption."

5) I'm not real sure what Yamaha means when they say a "secondary charge"......or if there really is such a thing, other than the intake of air created by this YICS passageway.

From reading the above Yamaha explanation, it seems that the motivations of the engineers were to create this "secondary charge" and inject it into the main intake flow at an angle (to create additional "swirl" and cylinder-fiiling potential), and YICS is how they went about doing so. The "balance" issue was secondary (or perhaps not even a consideration or an issue, good or bad), and the YICS tool was now needed to do a "proper synch"....each unit working equally hard (same as in the "old days" before a YICS passage existed)......

 

AF, the carbs have been off 3 maybe 4 times I am satisified they could not be any cleaner. The plugs are still a grey more then brown so I assume it is still lean. Rick is right, it takes very little movement of the pilot screw to get changes. Very little.

 

Chacal, I take it you endorse the colortune. Will it help eliminate the stumble on my slow speed side, or is it more suited for jetting the mid and high?

My pilot needle is what need adjustment.

 

YICS was a separate chamber in the head, with passages into the intakes. It was eliminated, apparently beginning with 1984 model year bikes, but remember the "model year" and what year you think your bike is may be two different things. IF you have a YICS-equipped bike, you DO NEED the tool to do a proper carb synch. If your bike is NOT YICS-equipped then there will be nowhere to insert the tool. What I can't tell you (maybe someone else can) is whether the YICS "camber" is still cast onto the outside of the head (and just filled in) or if they completely elimnated it. As far as I know (and fellow babies correct me if I'm wrong) all the YICS bikes PROUDLY proclaimed that fact, both cast into their valve covers and on the crancase end covers (both sides.) If you've got a YICS bike, you'll know it, if not, the tool doesn't apply.

 

The colortune is a very useful tuning and diagnostic tool; however, it may or may not help eliminate the situations that you experience, as the underlying problem may be caused by an issue(s) that a colortune can do nothing to address.

It is designed to allow you to properly adjust the pilot mixture circuit, which is primarily the idle/off-idle circuit. Mid- and high-rpm (or even lower rpm's under heavy loads and/or acceleration) is basically a main fuel circuit issue.

However, like the two halves of a ying and yang symbol, everything must be in smooth harmony for the bike to run properly.

By the way, the Holy Grail (i.e. the miserable, un-varnished truth of what a real chore carb tuning is going to be, written by people who actually know what they're talking about, rather than by people who are trying to sell you something) can be found at:

www.factorypro.com

and then click on the "Product Support/Technical Support" link at the top of the page, then on the "Motorcycle Tuning Tech" link, and then the "CV Carb Tuning" link........and then read, weep, study, and do. As you will soon realize, it's quite a bit of work to properly tune a carb to its optimal performance----another reason why we don't suggest using pods!

 

Great link, thanks.

 

I got mine all sync'd using the YICS tool that I bought off ebay. The instructions for using the tool say that it can be left in ! So, I left it in, and after I had gone for a decent ride, the bike no longer started. Its been a bitch for a week now since having it dyno'd with the tool in. So I decided to remove the tool - hey presto, she starts first time every time.

 

re: "that extra air" from YICS
It seems yammamamma and others' have a question about this mysterious "secondary charge" that is added to the main air stream.

This comes from the momentum of moving air in another cyllinder whose intake valve has just shut. Like water hammer in old pipes (modern faucets shut off gradually to eliminate this) the air moving through each carb towards it's intake has momentum. When you shut the intake valve that air "wants" to go somewhere. Connecting the intakes across to one another allows this momentum to go towards adding a "puff" to another cylinder's intake charge thus swirling it all up.

You ever watch smoke rising from a cigarette sitting in an ashtray? It's a very straight and skinny stream until a certain height and then gets very swirly somewhat abruptly. Thus skinny stream is called laminar flow. It's very "slippery" as it turns out and provides little resistance when moving through say an intake boot. This is good, it robs little power to draw such a charge of air through carburetors. the down side is that the stream of smoke is very pure smoke while the air RIGHT next to it is very pure air. It is only with turbulence that you get the mixing required for say, a good complete burn in the combustion chamber. So turbulance is good, right? well it produces a lot of drag.
Back to that smoke. Remember it gets all swirly at a certain height? This distance changes with the velocity of the stream, differences within the streams velocity (say from going around corners) differences between the velocity of the stream and the adjacent material, differences in temperature, pressure, viscosity, on and on. What you WANT is an intake designed so that you get enough turbulance to mix the charge but only at the very last so you don't waste energy pumping turbulent fuel/air.
It is quite a trick to design the length of the intake so that this happens. Especially when the air velocity changes with changing RPMS (piston speed)

Enter the YICS. As I mentioned above your XJ and mine has four (ok, two for some of ya) of these complex systems each working side by side and without the YICS they'd be flying solo on this crazy hydrodynamic mission. I won't bother going into the ins and outs of CV carbs (I'd be glad to bring my Hunter S style to bare on it upon request)
What the YICS does is use the above mentioned momentum of another cylinder's moving air charge to "puff" a drawn in charge right at the last minute, on it's way by the intake valve I believe. Just like blowing at that stream of smoke rising from the ashtray it disrupts that laminar flow on command.

the forgiving tuning of having intake vacuums balanced out for you IS as mentioned (I think by Chacal) a secondary bonus to the wrench doing the tuning.

 

I have got to get a Y-tool!
In the two years since buying my first YICS motor I've tuned without the tool...only because she feels great and can out runs all my "riding buddies" bikes.
Of course they have V-twins.750/1200 cc, 883 in. So far they haven't beaten the "moped"
That, and all the $$$'s have gone into reversing the neglect of the po.
But if it really makes a diff then I better look into it.
BTW, there is a thread somewhere on building a home made bottle sync
tool that I tried...works great and all for less then $7.00.

 

sorry for digging up this old thread But I needed it ...
I want to do a carb clean then set them up before it gets too cold
I found my 4carb manometer (amazing it still had mercury left in it)
but for the life of me i can not find my YICS tool
so a little google search I found instructions to make one thought I would share........
http://www.newmotorcycleparts.com/tools ... _tool.html
.
.
..........MXJR75OH

 

BAD DESIGN.

MAJOR COMPONENT(S) MISSING.

There is no provision for a seal between the 3/4" fender washer and the side of the cylinder block. The design of the tool provides no way to compress such a seal in its present form.

As shown, the tool would allow a vacuum leak at the cylinder block, on whichever side you inserted the tool from. The outermost YICS port is to the outside of the outer seal on the shaft.

 

would it be a bad edit to ask someone here to take a picture with a tape messure of there YCIS tool ...or could you recomend were i could purches
another one ........
.
.
..................... Thanks MXJR750Oh

 

XJ4Ever has a proper replica of the factory tool, if you want to buy one.

PM member chacal or email info "at" XJ4ever "dot" com.