To use or not - YICS Tool

Well I'm sticking my neck out. I've been naughty and did the sync without using the YICS tool. It works perfectly - Spark Plugs looks exactly the same and with a good color, idle is very smooth and it pull like h...
I've just been lucky or?
(of cause the carbs are clean, the valves are done, float hight checked and with a new air filter)

 

OK, worms you want, worms you got.

Here's the situation; hang on for the arguments.

You may have gotten lucky; OR you were close already; OR it's not as sync'ed as you think (and could even be better.)

Here's why: YICS tends to act as a "damper" or "equalizer" in the intake tract. Anytime you're measuring/adjusting one cylinder, if the YICS is still open then that cylinder is receiving secondary intake vacuum "signals" from the other three cylinders. This secondary intake can act to "mask" a slight out of sync condition. So what you get is this: Sync'ed with YICS open, you could still be slightly out of sync, and can't tell. Sync with YICS blocked, and you'll still be sync'ed with it unblocked.

 

i'am not saying anything

 

Listen to Fitz. You can't balance vacuum properly when they are sharing vacuum. The japanese guy who designed this engine knew this and put a place in the engine to put a tool so you could sync. That is why that gallery port is the way it is.

 

Close enough is good enough sometimes. This aint rocket surgery. : )

 

Rocket surgery LOL we say that at work all the time!!!!

 

"Close enough is good enough" does only one thing, my friend--

It shortens the amount of time/miles before you need to REVISIT and DO IT AGAIN.

Don't get me wrong; I love working on old bikes or I wouldn't be here; I DON'T however, want to keep doing the same thing over and over.

I prefer "set it and forget it" (for 5000 miles anyway.) Lots more time to actually ride and enjoy my XJs.

 

Yeah?
If its idling and running good he cant be that far off sync.
It might be dead on.

 

It maybe good enough to ride. But it isn't right.

Unless he's got the one engine where all 4 jugs are pulling exactly equal vacuum there's a difference. The YICS removes the difference unless it's blocked off.

 

Which came first, the chicken or the egg? And, should you hire the fox to guard the henhouse, just because he offers to work for a lesser wage?:

D. Verhey sez:

 

See? Worms, I said. Big can, open again. But it shouldn't be.

Yamaha built the bike.

Yamaha made the tool and said "use it."

Yamaha HAD a reason for that.

That is all I need to know that I need to use the tool, period.

Yes, we can argue all day about how close you may or may not get it, and all of that is very true. However, the pure science behind it says you will get more accurate results with the cylinders isolated. And that much IS true, based on my own, real-world experience and a comparison done with a Morgan Carbtune with and without blocking YICS.

YICS does "dampen" out an imbalance, especially at idle, as above. Block it and you remove the dampening/compensating effect. Pure and simple. HOW MUCH effect YICS was having we can debate until there is no more horse left to beat and the can is empty, but if you block it you eliminate it from the discussion.

But then again, what do I know. I put another 120+ miles on my XJ today, and it started/ran/idled flawlessly, even in stop-and-go rush hour DEEtroit traffic. Just like it has for the last 3600+ miles since I got DONE with it.

 

Hey, pirok, if your yics ports are blocked, that is your built in YICS tool.

 

the "hole" your blocking off on a 750 is about 3/32 inch or 2.38 mm, minus any crud that may be in there

 

I am with Fitz on this one for sure....
I know how my bike ran when the sync was close and I know how it runs when it is perfect! Night and day difference!
The tool isn't expensive and once you have done it a few times it is easy.
Be nice to your bike and get the YICS tool and do it right. You'll be glad you did.

 

Did you sync your carbs after you got the carbs back from being cleaned?

 

I used to think you needed the tool, but after thinking about it and reading the procedure I now disagree. I don't recommend against the tool, but I think with the right tools the purpose of the YICS blocking tool becomes moot.

Heres what I (currently) believe:

The Yamaha engineers were not wrong...but they wrote a procedure using a single vacuum gauge. If you tried to sync without the YICS blocked with a single vacuum gauge, every change you made would affect the other cylinders, and you would be syncing for a really long time...enough to heat up the engine too much, and enough to make you start looking for a better solution. The solution is easy, just block off the ports and you will no longer have to worry about the effect of changes on the other cylinders.

A Carbtune, though quite useful, has a resolution available limited only to the resolution of an individual barometer The smallest increment on the carbtune is 5 mm Hg which is equivalent to 2.68 inches H2O. You can get a resolution with a manometer of 1 mm H2O, or .04 inches, or 67 times the resolution!

However, if you built a contraption like the one I made, that allows you to use valves to switch between cylinders very quickly so that you can dial in the sync in a way that you can't with a single vacuum gauge or a Carbtune . A manometer is the most accurate vacuum COMPARISON device you can get.

So in conclusion, I believe Yamaha advises the use of YICS port blanking due to the tools available, not the inherent nature of the YICS. I also think that a bench sync followed by a manometer that has vacuum lines that can be quickly switched to different cylinders can provide sufficient resolution to account for the dampening effects of the YICS, no matter how big or small they are. Ultimately, I believe that a sync in normal "running" conditions will account for any discrepancies with the YICS, which cannot be accounted for if the YICS is blanked off. Especially the manner in which the fuel burns, the forces exerted on the piston, and the heat and velocity of the exhaust. Let's be honest, blanking off the YICS alters the way the engine runs in a significant way.

Of course, it's probably just easier to throw an oiled rag in there an be done with it. Easier, however, has never been my nature.

 

I remember someone did a write up they synced the carbs with the yics open. Then they blocked the yics and found up to a 5mm difference so they adjusted it with the tool in place. Then they took the tool out and checked the sync and it was still right on.

So I vote block the yics passage.

 

Bill, You are hard to figure out sometimes.
This was a silly question.... Of coarse I did.
I did a Sync then a colortune and then another sync and another colortune. This way I knew everything was set up perfectly and my bike runs better than anything I have ever ridden. And I have ridden a lot of bikes over the years.

 

Well, that's a very interesting idea, and a good point.

The early Euro XJ550 (1980 yics) service manual does indeed show a single, "switchable" vac gauge in the maintenance section when discussing the synch procedures; however, all of the US service manuals (for 550, 650, 700, 750, and 900 models) show what is obviously a carbtune-type, 4-column device.

 

I guess that reduces my point to only the available resolution of the device, and nothing to do with the problem of moving the gauge between cylinders.

What was most commonly used in 1980 - 1986, though? Is it possible that the engineers wrote a procedure for a device that is different than that shown in the manual?

I've already changed my mind twice! Give me all your money or I'll do it again!

 

What is so hard to figure out? I ask questions. Im glad you knew the answer.
I would certainly hope it runs good after all the time, money, effort and experience that went into your carbs.

 

Ah, because I just got done saying in my first statement how you should take the time to do it right and then you asked me if I did it right?
Hello!

 

Wasn't sure because I thought someone else synced them for you.
I guess it was done right about 4 times.

 

Bill, when the carbs are rebuilt they are what you might call a pre sync, by measuring each one but this is done to just get them close. Once you get the rack of carbs back on the bike then you have to do a vac sync to get them perfect. This is something you have to do yourself.

 

Per my factory service manuals; XJ550RH 1st Edition, October 1980 and my 650 Seca book, which is a hybrid based on the XJ650G (1980) they both specify the use of "Vacuum Gauge, TLU-11080-30-02" even though the 650 isn't even a YICS motor.

That vacuum gauge is a 4-tube manometer, similar to the CarbTune. As chacal pointed out, I've never seen a reference to a single gauge in a factory book.

The most common device back in the day was a product called "Carb Stix" which was a 4-tube manometer with MERCURY in the tubes, like the early CarbTune. I'm sure a lot of dealers used the factory tool, but I'm willing to bet a lot of them were using the much less expensive "Carb Stix." It was pretty much "common knowledge" in those days that you needed a 4-tube device to sync a 4-banger with.

 

(I'll throw in my worms)
From the point of view of Yamaha - Japan, the American service tech may have been thought of as (possibly) less competent, and since he's using a $20,000 Gas Analyzer, why not make him use a FOUR DOLLAR YICS tool for speed and accuracy. As a bonus - the customer would be totally awestruck at the expense and complexity of the tune-up proceedure that they would never think to be able to replicate this in their garage and get it right.

I currently feel that the NOOBS should "stuff it with a rag" the first time they tune, and spend that money on new rear brakes.
The Noobs should devise a dead simple "loop type" water Manometer and restrictors as their FIRST sync tool, then morph this 20 feet of clear tubing into a 4 tube water Manometer later on.

I agree with Fitz that the person who does the extra effort in ALL things will have a more enjoyable riding experience and peace of mind, and those who cut corners and do "good enough" work will ride with a nagging, annoying feeling of "what if".

 

by "water" Time means ATF on the off chance it gets sucked all the way into the intake. THERE'S a "what if" I like to cover my arse against.

 

Well it's hard to argue against the YICS tool from a logical point of view, but in practice: what is valid for cylinder #1 must be valid for all the others and it's a quite tiny hole - 2.38 mm. What ever the pressure/vacum is in the YICS tube it must be almost the same at the #1 hole as at the others. Then you have the reduction of the impact of the pressure/vacum on the other side of the tiny hole where you actualy measure the pressure/vacum with the manometer in your sync tool.
So is it only some pedantic mumbo jumbo, or? :wink:

 

Not quite. The pressure in the passage isn't constant, it's "pulsing" from the fact that all 4 cylinders' intake tracts are connected to it, but each individual intake valve is open at a different time than the others. So when the valve on the cylinder you're measuring is closed, all of the others aren't and vice-versa. When you're measuring vacuum with YICS open, you're getting a "signal" not just from the cylinder you're trying to adjust, but a combined input from the other three as well, which causes a "damping out" or compensating effect.

So no, it's not mumbo jumbo, it's a way to make the adjustment more accurate than you could possibly get it otherwise (except by pure luck.)

"Right on the money" vs. "close enough" is what it comes down to I guess. I do know it's a heck of a lot quicker and easier to get the bike idling like a sewing machine with YICS blocked and a 4-tube manometer.

 

Before "Gang Gauges" and "Carb Sticks" ... you did an Old School Sync.
ONE Vacuum Gauge.

Set-up fans so the Bike don't overheat.
Use an Aquarium Gang Valve set-up, ... saves huge time.

September 16, 2006
One Gauge Sync
By: Rick Massey

Revised: I don't do all the Golf Tees anymore. I use an Aquarium Air valve Set-up.

http://xjbikes.com/Forums/viewtopic/t=2 ... +sync.html

 

A 4 cylinder in line engine is quite symetric in operation so the pulsating condition must be the same for all cylinders intake.
If you do the sync with the YICS tool you are making the sync in a very unique situation wich will never occur in an ordinary working condition. If you do the sync witout the YICS tool you are making the sync as the condition actually are at the intake!

BTW. Thanks for your patience with my silly questions.

 

:wink:

 

This question becomes more interesting each time it is asked.
It comes down to... If you want to ride and do not have the correct tools, you will find a way to ride.

 

I synched with the two bottle method and the blocking tool inserted the first time I synched my carbs. I was pleased with the result but not thrilled. I then purchased one of those 4 guage Barracuda manometers that are being sold on ebay for like $50. Then I rechecked my carbs and they were close but slightly off. I resynched w/o the blocking tool the second time and it runs smooth enough so that some of my fellow co-workers that are also mc riders have commented at how it sounds.

Having done it both ways I am inclined to agree with Polock. Does that mean I will never block the ports in the future - no. But if I have 30 minutes some Saturday afternoon and want to tweak my carbs in I will probably pass on the blocking tool.

As an engineer who works in an R&D environment I can tell you that a lot of the decisions that are made are CYA moves.

I love these discussions though. I learn something every time. This is a truly gifted bunch of guys on this forum and I am thankful to be able to be a part of it.

If any of you are familiar with Mortimer Adler, he was an intellectual who developed a reading program that he called "The Great Books" which he considered to be essential reading to be a well developed thinker. One of the things that he said is that each one of us are born and are immediately swept into the current of human history and become a part of "The Great Discussion". That is, we learn from what others have thought in the past and then we in turn pass on what we have learned to subsequent generations.

Not all thoughts are equal. Some ideas are just plain bad. But if we attempt to learn as much as we can from each participant in "The Great Discussion" we will benefit more than if we put on blinders and refuse any ideas other than from those who agree with us. That doesn't mean we have to agree with each other.

Best wishes to all and thanks for this forum.

 

pirok:

The Engine's Carbs are Synced only when the YICS Tool is used to ISOLATE them from one-another.

You may do as you please.
But, your generalizations about how the 4-Inline YICS System is incorrect.

If you think there is little difference.
Remove one of the Plugs to the YICS Passage and see what happens to Performance.

A correctly done Vacuum Sync is paramount to PEAK Performance.
Once the Vacuum Sync is correct; other Fine Tuningn can be done without the Tool:
> Plug Chops
> ColorTuning

Fine Tuning he Engine the way you'll be running it.
That makes perfectly good sense.

 

My 2 cents...the tool is important for all the reasons Rick posted. What I can contribute is a better mouse trap.

Buy a tool from Chacal...easy & supports the XJ cause.

If you DIY...the YICS tool measurements on the web are correct. To improve:
- Use 3/8 SS tubing 316 or 304 grade for the tubing required.
- Use heat resistant tubing instead of fuel line to block the ports.
Here's the tip:
+ Use Polyimide tubing, resists to 896F. Problem is thin wall so you have to cut a piece of silicone spark plug wire with the center removed and insert in the tubing. 3/8 may not be available.
+ Or, Silastic tubing, resists to 480F. Thick wall, proper size but you still need to insert another small piece of silastic tubing inside. Broad range of tubing available. #R-96115-26 is the proper OD. You need to decide what kind of insert tubing to use. Tubing can be purchased by the foot from Cole-Parmer 800-323-4340.

I used the silastic with a plug wire insert. It has the flexibility to seal the YICS port and because it is SO flexible, it seals the entry so there is no need for a special seal on the wing nut side of the tool. With a fan on the motor and idling, I ran for 10 minutes without melting.

Hint: Decide what your time is worth. Chacal makes it worthwhile.

 

Yeah there is. If the tool has three sections of tubing, there's a YICS port "outboard" of the last one; you still need to block the opening on whichever side you inserted the tool from. The blocking occurs between the YICS ports. The tool only blocks it from its neighboring port, you would still have it open to the outside.

 

Thanks all for your replys!

I will come back to to the issue when I have made a YICS tool and tried to sync without the tool and then see if there is a difference in the reading with the tool in place.

 

At the risk of beating not just a DEAD horse, but one that has already decayed, decomposed, and been ground into bone meal dust and used as landscape fertilizer in your tomato (or, tomahto) garden, here goes:


Does the sun "rise in the east, and set in the west"? Is this is a silly question? Read on....

The little saying above is a good example of the mistakes in thought that occur when the fundamental operational understanding is missing, or just plain wrong.

The Sun "rising" and "setting" statement is a throwback to medieval times when the Earth was thought to be at the center of the universe; that vision of "how the universe operated" was firmly embedded in the minds of, well, EVERYONE, and thus led to all sorts of amazing and fantastical models and methods of describing how and why the stars appeared in the skies, the cause of the seasons on Earth, the place and role of humans in the cosmos, etc.

In fact, it was in the late 1500's, when the Church started to get, umm, concerned about the lack of food necessary to feed the rapidly growing populations of Europe that it began a search for a better way of predicting the seasons----and thus when was the best date to begin planting crops (and thus getting maximum food production..........plant too early, and you wipe out an entire year's food supply-----not a real good confidence builder among the peasants; plant too late, and you don't get enough of a harvest to feed all those hungry bellies, and hungry bellies lead to riots and government /papal overthrows----very bad form, if you're in the "ruling-the-rabble" biz.......).

So, in their quest to find a way to prevent finding their own heads on spikes outside the city walls, the Church sought out the recommendations of "science" to come up with a better method of predicting the seasons, which of course led right back to the study of astronomy, and which eventually led to the destruction of the ages-old "earth-centered" understanding of the planets and the Sun, and ushered in (after lots of gnashing of teeth and tearing of tunics) the understandings of Copernicus, Kepler, Gallileo, etc. who were eventually allowed to have their say and were shown to have actually invented (or recognized) a better (truer) mousetrap.

But still, old habits die hard; watch any local weather forecast the world over, and they still tell you what time the "sun rise" and "sun set" will be tomorrow.

Moral: having the correct understanding/vision/"theory" of what is really happening is a Really Useful Guide to coming up with correct solutions to any variety of problems or issues.


THE THEORY OF YICS:

The Yamaha (or any) in-line, four cylinder engine can actually be thought of as four (4) individual engines, with each single-piston engine producing a certain amount of output (horsepower, or, more precisely, torque). Since those four engines have been "chained together" to produce a single "engine unit", we need to have a way to coordinate the power output of those four individual engines so that they neither fight against each other, and, for best output, economy, drivability, and that "sewing machine" type of "performance", that they each produce the same power output. The equality of power output from each cylinder is what creates the maximum total engine output and "smoothness".

The equality of power output from each cylinder is called synchronization:

–verb (used with object)
to cause to go on, move, operate, work, etc., at the same rate and exactly together


Note that it is not the carbs themselves that need to be "synchronized"; in fact, the adjustment of the throttle plate positions screws, called the "synch screws", will typically all be set to differing positions on each "set" of carbs during the synch process; the carbs are not set to be "in synch" with each other, but are each set differently in order to achieve the greater goal, the real goal, the actual goal ---- the "synch" of the entire engine unit (so that each cylinder is producing the same amount of power).

Let me make a statement here: until you understand the above, you will never, ever, understand the process that you are going thru, and you will just be like a blind man going thru this step, and then that step, and then the next step, and if something doesn't go right........well, then you're lost. You'll feel like one of those ancient astronomers who are still trying to shoehorn square pegs into round holes and twiddle and fiddle with re-arranging "the crystal spheres in the heavens" that the planets glide upon or multiple layers of (invisible) fulcrums, levers, gears, and sub-gears that regulate the observed motions of the planets (especially Mars, as it appears to go "retrograde", i.e. it moves forward thru the sky for a while, and then, all of a sudden, it moves "backwards" in the night skies---that was the reverse spur-gear kicking in, by the way) because you're stuck with a mental "understanding" of how the system works THAT JUST AIN'T SO, JOE.


Okay, back on track: we've got to equalize (synchronize, "to cause to....work...at the same rate and exactly together") the power output of each cylinder. Now, pray tell, how might that be achieved, given that each cylinder might have slightly different bore dimensions, ring seals, wear, are driven off different cam lobes, each of which has a different wear pattern on it, etc.?

Oh, and by the way, keep in mind that since we can't hook up an engine dyno to each cylinder and measure it's unique power output, we're going to do the next best thing, and measure the strength of the vacuum created by each cylinder as a "proxy" of the actual torque output, using the rather well-established theory that a cylinder that can produce the same amount of vacuum draw (pressure drop) in an air column is doing the same amount of work as another cylinder creating an equal pressure drop. NOTE THAT THE CYLINDERS DON'T HAVE TO BE IN THE SAME PHYSICAL CONDITION AS ONE ANOTHER in order to achieve equal amounts of vacuum draw; you could, in theory, have one 50cc cylinder and another 1500cc cylinder, or one that is brand new and one that is horribly worn out of the same size, each producing the same power output (vacuum draw), and they, too, would be "in synch" with each other if they were driven together in a single engine unit......

And note that we don't even measure the vac signal at, or on, the carbs, we measure it on and at an entirely different point, AFTER the carbs, at the intake manifolds.


Now, how can we adjust the power output of each cylinder? I know! We can increase or decrease the thickness of each intake valve shim, thus changing the amount of fuel that enters (and the timing of the fuel entry) into each cylinder, thus increasing or decreasing the power output of each cylinder depending on how each intake valve is shimmed. So, we hook up our vac gauges, observe the vac strength of each cylinder, and then pull off the valve cover and pull out shims from various cylinders (valves) and put in a thinner or thicker shim, button it all up again, start the engine and observe the vac signals from each cylinder again, shut it down, cool it off, pop the valve cover off again, fiddle with a couple of shim swaps again, and repeat until the vac signals are equalized.

Right? I mean, changing the valve openings (via changing the intake shims) WILL work.

And if you want to "fine tune" the engine, you could always go the "next step", and also change the exhaust valve shims in conjunction with changes in the intake valve shims and trial and error various combos until you got the power output from each cylinder equalized, i.e. "in synch".

After about a month or so, you'd have a fine running machine.

OR, you could leave the valvecover on (assuming the valve shim clearances are already within their proper clearance specs), and simply add more or less fuel to each cylinder, a plan that will surely increase or decrease the power output of each cylinder, too...........and with a lot less effort......just turn a couple of screws and adjust the position (opening) of the throttle blade in each carb. So carb 1 has a slightly larger throttle opening than carb #2, which in turn is a much smaller opening than carb #3, etc.......

Note that the "carbs" (and their throttle opening positions) are NOT equalized, and since their throttle opening positions are not equalized, neither is the amount of fuel flowing thru each of them at any rpm or load. There is absolutely not any single thing, AT ALL, that is "synchronized" about the carbs themselves; their throttle plate positions, their fuel flow rates, nothing. By design, the carbs are un-synchronized in relation to each other in order to get the entire engine synchronized.


But wait, there's more!: to "fine tune", you're going to have to "un-synchronize" the carbs even more: whereas you may have started out with the pilot circuit mixture screws all "synchronized" at 2-1/2 turns out (when you rebuilt the carbs), you're now going to fiddle with each one of them to further change the power output of each cylinder until you can get each cylinder's power output in harmony with each other. Note that changing the pilot mixture screw position on carb #1 (to that nice "bunsen burner blue" combustion color) will increase (or decrease) the power output of that cylinder, thus throwing the engine OUT of synch, and you will have to re-synch the entire engine (via the carb throttle plate position adjustment, i.e. the "synch screws" on the carbs) after each individual cylinder is "colortuned".

Did you notice that changing the position of each pilot mixture screw serves to further throw the carbs "out of synch" with respect to each other? The settings on each carb are purposefully thrown "out of synch" with each other in order to achieve the "engine synch"? We've sacrificed the uniformity and "perfect equallness and symmetry" of each carb in order to achieve a greater good?


Good, now you're thinking right and getting real!

Now, what about that YICS system? What does it do? It SHARES vacuum between the four cylinders via the long YICS chamber cast into the back of the jugs? Is that what it does?

Oh yes it does........

And is the PURPOSE of the YICS passage/system to create an equivalence of vacuum between all four cylinders?

Oh NO it isn't.......


And so should you purposefully allow vacuum to be shared between cylinders when synching the engine?

 

Thanks chacal. I think i got the picture now.

 

This is the best description of WHY the blanking tool is necessary, even though it's not a normal running condition. In short, you can't get a reliable reading of the strength of the vacuum of an individual cylinder without blanking the YICS.

Moral of the story....the best sync is achieved with a Colortune, a YICS blanking tool, and a 4 cylinder manometer.

Bench Sync, Sync without tool (get it good enough to Colortune), Colortune, Sync with tool, Colortune, Sync with tool, Sync without tool(to double check your work)???

From what I just read it seems like a Colortune is as much or more important than the blanking tool.

Honestly, since we here on xjbikes.com determined that you could just stuff an oily rag in the passage to blank it off, I've always thought the point was moot.

I just didn't understand, until now, why a sync during a normal running condition wasn't going to be better. If we could somehow get an accurate power reading from an individual cylinder without blanking the YICS, then we wouldn't have to blank the YICS!

 

Bingo! Pick any prize from the top shelf........

 

Ok...are the 12 series shocks on the top shelf??? I'll take a set of those! But a headlight will do.

 

I prolly shoulda posted this 3 pages back (visual aid

 

8) Thank ya' sir!!! 8)

 

Fitz that is SO cool!! Man ... talk about a picture being worth a thousand words!! My hat's off to you!