"YICs TOOL" VERSUS NoN YICs tool carb sync ...

Im curious to see how many of the people on here sync with or without yics tool.
I am under the impression that both work but interested in a vote.

 

Bill, you can edit this thread into a survey thread.

I've come to the conclusion that the tool allows the Factory Authorized Tech to arrive at a "perfect" sync FASTER than not using the tool.

I also buy into the line of reasoning that, since you drive with the port unblocked, you should do your final tuning with the port unblocked.

 

I say we go for a vote (survey). This will surely open a heated discussion.

 

My thoughts exactly, but hey what do I know. Got my bike 7 weeks ago and am just done cleaning carbs for the first time ever. They're not even back on the bike yet. :roll:

 

Guys.... Im gonna try and repost this as a survey.

 

It's not a matter of opinion, it's science, pure and simple.

The YICS tool isolates the cylinders from each other to allow individual tuning. Without the tool, the YICS passages from the three cylinders NOT being worked on are feeding charge to the one you are trying to adjust, and affecting the reading on that one.

While it IS possible to get quite a good tune without using the tool, it is IMPOSSIBLE to be 100% accurate unless each cylinder can be isolated.

With YICS "open" the secondary charges can throw your readings off enough to fool you into thinking you are balanced when you are not.

With the cyllinders isolated, the variables introduced by the YICS system have been eliminated, and you are adjusting ONE cylinder at a time. Which is the whole idea.

 

OK.. Well I'm new to YICS so excuse the ignorance here, but am I right in thinking that YICS is simply a small passage between the carbs that allows the pressures to equalise between the chambers while the bike is on the road.. A sort of self balancing carb set up if you like?

If this is true, then while those that are for using the YICS tool are correct that isolating the chambers will allow you to more easily accurately balance the chamber individually.

However, those who are for balancing without the YICS tool are also correct.. So long as the chambers are showing as balanced without the tool, while the bike set up as it would be on the road, it makes no difference what so ever that you didn't have the tool.

You can do this either way, it's probably easier with the YICS tool, but the end result is what counts.

Personally I'm going to have a go at balancing my carbs without the tool, because I haven't got one.. If I find I can't do it accurately enough, I'll make one, then have another try.

 

Just Colortuned mine a week ago without the YICS tool, and then a friend of a friend had one for me to borrow yesterday... The colortune did remarkably well for tuning without the tool, and the high rpm powerband was amazing.

I did find that I was able to dial in #3&4 a tad better with the tool and the colortune, but I am keeping a close eye on gas mileage, so we'll see if it gets even better. Prior to bench syncing & colortuning, my carbs were so out of whack my mileage was dismal... 35mpg on average. She was drinking gas like a beer bong. Now it seems much better(even though I've only put 135 miles on it since colortuning it)

 

I know the tech manual says to blank off the yics, and I understand why, if you are syncing using a vacuum gauge one cylinder at a time. It would take forever to go back and forth after changing one cylinder to see how it affected the last cylinder.

Is that how the manual says to do it? Or does the manual use a manometer like most of us use?

The crux of the argument seems to be this:

The manual says to blank the port, but why do the carbs need to be synced individually, if they are then run with the yics port open.

In other words, how could a "blanked sync" possibly be more accurate than one that mimics the normal condition.

I see how that is true if using a single gauge as I mentioned above. But when you are comparing cylinders against each other? They automatically adjust to each other, which is another way to eliminate the variation induced by the yics.

What part of "synchronization" implies a need for "individuality"? You need 2 to sync.

Real science would do an experiment.

Sync using a manometer without the blank. Then test with a gauge with the blank installed. Note the individual variation numerically.
Then, sync using manometer with blank, test without.
Of course sync and test without the blank.
For a control, sync with and test with blank.

Get the standard deviation between the cylinders from the gauge reading.
Determine which results in all 4 cylinders being closest together.

Hmmm....who here has the tools and the time? Of course we can get results from many different bikes, that would make it much more accurate.

 

And make sure the tiny vertical ports are cleaned out before you start,(almost impossible without removing the head)

 

The reason we sync carbs is to obtain an equal amount of fuel air mix into each cylinder.

The Yics ports work as a connection between each cylinder so in effect they allow a certain amount of self balancing. At idle it will compensate for out of sync carbs a reasonable amount due to the higher vacuum at idle.
This is the argument used by the tune the carbs as they are in real life fans.

But while this is true at idle, at part throttle openings there is less vacum and higher flow, and the Yics ports will not have as much effect. So an out of sync carb will now not have the same air flow as the others and the lower flow will cause the slide to open less and mixture will be affected.

If you can get the sync close without the tool, fine. And if you get the carbs perfectly balanced then there is no issues anyways. But if you can get a tool to use, do so.

If the ports are gummed up you effectively have a permanent Yics tool

 

Not quite.

The passages interconnect the intake ports just upstream of the head of the intake valves. They feed a charge from the three cylinders that aren't on an intake stroke to whichever one is.

What you're talking about is a balance tube, not uncommon but not YICS either.

day7a1 I've DONE a limited version of said experiment; it is possible to achieve what the manometer (4-tube type) claims is a balanced motor (although a bit "shaky") with the tool out; only to then plug the YICS passages and discover that one cylinder was way off but being "masked" by the YICS from the others.

Once the motor was balanced with the tool IN, then checked with it out, it was still balanced of course, but then very steady on the gauges. Also MUCH quicker to tune right in with the passages blocked; with the tool out, lots of fiddling.

I would imagine that if you were using an EGA to sync (like Yamaha did at the factory) the tool would be IMPERATIVE to any degree of accuracy; plus cut final production time drastically.

Like I said, the use of the tool is pure science; Yamaha wouldn't have designed, produced, and specified its use for syncing the YICS motor if it wasn't necessary.

I learned a while back the futility of trying to out-engineer Yamaha's legions of engineers. You get much better results if you follow the book.

I guess it depends on whether you'd rather "set it and forget it" and ride or spend hours fiddling trying to lose a slight hanging idle or low-to-midrange hesitation.

I'd rather ride.

 

Fitz...i'm curious. When you say it way way off was it way high or way low? I'm just working on a good theory here, to understand what's going on better.

Also, how in the world does one sync with an Exhaust Gas Analyzer? If that is what the EGA is, I really want to know how that's done. Does that mean we can adjust the pilot mixture with a vacuum gauge? (I'm kinda joking here. I've heard of it being done, but I don't trust the methodology.)

Furthermore, can you discuss the air/fuel mixture as it relates to a proper sync, in terms of the process and limitations?

 

So...I made a YICS blanking tool with a strip of old T-shirt, some olive oil, and the ability to tie a knot. It was really easy to put it in the YICS port. It clearly fit tight enough to block the ports. Each knot was about 2-3 inches apart, there were 8 or 9 knots in the port. I synced beforehand. It wasn't perfect, but it was pretty close. However the idle was still kinda lopey, and things just didn't feel right.

The results were AMAZING! I am sold on the YICS blanking before sync. For the first time ever, have enough torque to move the bike along at idle while moving slow (important for a commuter!!) I had to rev it up a bit before. #4 was WAAYYYY off. I use an inverted 2 bottle sync homemade tool, and the fluid was being sucked all the way into the bottle. I had to turn it a bunch to get it straight. The rest were ok, kinda like Rick's experience.

Here's my theory, and I mean THEORY, maybe even hypothesis. Yeah. Hypothesis.

There are standing waves going being created in the port during normal running. Do to wave interference (click on the first line, wave propagation), there are likely several points where the YICS port diameter and length will cause an equal vacuum to appear, but only one of those is where all have the same root value. I'm thinking of this like a musical chord. We are looking for 4 root notes, but without the blanking tool we can get a root, root, root, and octave, which will also cause the 4 cylinders to appear synced, like a good chord sounds like a single note.

These modes allow the cylinder to balance at certain frequencies (rpm), even though the cylinder isn't equal across all four. When you blank the port, you remove the standing waves in the YICS port, thus removing the influence of the 3 cylinders on the 4th. This allows one to find the one "first order" mode. The only sync we really want.

This explains why some people have been able to get a good sync without a blanking tool. You could come across a first order mode combination without using the blanking tool. But it would be hard to do. A really good bench sync would help, I would imagine.

It also explains why, after syncing without the tool, we typically find one cylinder WAY off. That cylinder is at the modal position, and is suffering from wave interference, causing it be be either much higher or much lower than what is really is.

What d'ya think?

 

what was your process for inserting the tee shirt + knots?

 

the way i look at this is like this- you're trying to cut 4 boards at equal length, without the yics tool you have someone shaking the boards as you're trying to measure and cut... you may get close, but it wont be perfect, with the yics tool, the boards remain stationary

 

I got it from a post by rickcomatic. Take a long 2" wide strip of t-shirt. Tie it in knots as frequently as possible. Soak it in oil, even olive oil will do.

I had to run a metal hanger straightened out with a little hook at the end to pull it through the YICS port. I cut the ends off then re-capped both sides of the port. I could tell the knots were pretty tight in the port.

To get it out I had to use some tweezers, but if I had a thinner set of needlenose that would have done.

 

Thanks

 

I think that's really interesting and even plausible... best hypothesis on YICS I've heard! And I agree with bigfitz, Yamaha wouldn't have put all the effort into this and created the tool if you didn't need it.

 

If they hadn't made the YICS they wouldn't need a tool.

 

Ok.. Well there we have it Ladies and Gents, a proper comparison.. Thank you Day7a1 for posting that here.. I'm sold on this now.

I agree with Wizard, my XJR doesn't have YICS, and it runs like the brutal machine it is.. However my XJ does, so I'm going to block the ports with an old teeshirt soaked in olive oil when I balance them.

Just a couple of questions:
What colour was the teeshirt?
Was it ordinary or extra virgin olive oil?
What kind of knot did you use?

Sorry.. Only joking.. Thanks for the input, it was really useful. Although I am curious as to whether the bike runs ok or better than ok if you completely block the YICS ports and ride around like this, like an ordinary motorbike.

 

extra virgin, but you can't get them in Melbourne ~0)

 

Isn't the only diff between a yics motor and a non-yics motor
the yics gallery?
And My feeling is the legions of engineers realized their own
folly by discontinuing the gallery entirely.

 

The jets on my 82 XJ650 YICS carbs are smaller than on the 81 non YICS XJ650. I do get 50 MPG with the smaller jets, same horsepower, less fuel.

 

KA1J- According to Chacals catalog, the fuel jet sizes are the same, but the main air jet is substantially larger. Remember the late 70's and early 80's, I think no one wanted to use more fuel then, it was all about getting better mileage, i.e. more power for the same amount of fuel. If you can burn more of the fuel that you have the more efficient you are.

This paper shows that even in 1995, YICS was improved upon, not done away with. GM used a similar system as well with their Vortec engines, at least in 1988.

Todays technology is better, but to imply that YICS was a step backward is like saying that mainframe computers are worse than no computer at all.

Sure, today the technology sucks, but it was the best out there at the time. If you want to improve the system, buy a new(er) bike.

 

Not a step backwards-mearly a miss step. An idea that looked
great on paper but only yielded moderate results in the field.

Just the fact that you can get close results with or without
the tool.....results the avg rider would't notice.....kinda tells it
all, don't you think?

Yes fine tuners like us can readily tell the diff. but
the avg rider has no idea how their plugs look, let
alone something like bal. carbs.
And believe it or not THATS how bikes were made in those day's.
For the avg rider-not the aficionado