convert your non yics engine to a yics, 20 minute job

well i did this mod on my lunch break it starts, idles, takes off,runns and accelerates alot smoother than it did. it was already synced up pretty good, this feels like iceing on the cake. i guess i dont realy care if it gives me better fuel eccomomy, it feels great. BUT i am pissed at myself because i droped the tank and put a flat spot on the top right curve. (any one got a good tank at a good price) but it was already dented on that side and it isnt too bad. all in all it is cool to have tryed his mod.

 

Well, I tried it too. I've very recently done a valve job, sync and colourtune and sync some more. And I was running pretty good - easy to start, decent idle, no flatspots. After making the mod, I seem to have a stronger idle, faster takeoffs and just generally better performance. for the few dollars and few minutes it took, it was worth it

 

accel at speeds is much more powerful, i felt much less vibrations, the only thing i noticed that was not a total plus was there was much less engine brakeing, but i think this will give me a little bit better gas milage. i will let you know tomarrow as to whether or not there is a change in gas milage.

 

The Vacuum Port Link-up isn't going to be TRUE YICS. This we know.

But for less than 5-Bucks for everything you need ... and, being able to switch-back to Normal if the experiment doesn't work-out ... then, how can you go wrong?

I don't really know what the net effect will be.
It "Seems like" there would be a Balancing effect -- In theory.

With nothing to lose ... if someone is willing to try this and submit a "Before and After Report" ... then, why not see what happens?

I don't think it will substitute for actually Synchronizing the Rack as you do with the four separate and pulling the Intake Stroke Vacuum.

But the experiment is cheap and harmless and if you want to try it to see if the Bike will run better we won't say no!

How's does that work?

 

ok Rick
here is my report:
before --Good
after-----Very good
wrenchmaster

 

Fine.

Then, take it a step further. Fine-tune the Pilot Mixtures with the Vacuum Lines linked-up, too.

Read the Plugs and see how their Coloration is.
If they are too light; add a couple of DEGREES of Richness by Tweaking the Pilot Mixture Screws out the width of a Nickel.

To Dark:
Go the other way a couple of degrees.

But, don't do them all IF only ONE needs the tweak.
Read the Coloration on EACH Hole and tweak EACH Hole individually AS NEEDED!

 

A good idea Rick, I am always looking for a finer degree of tuning.
My idle mixture screws have the coarse threads rather than the fine threads found on 82's and later so turning my mixture screws changes the metering with a lesser degree of turning than the fine threaded ones, they are very sensitive.
First a new set of plugs and you will have a report.

wrenchmaster

 

Balance tubes are nothing new and help idle smoothness. YICS added the inlet port to promote fuel suspension.

 

You will not get a consistent sync.

The passages are cast in place, not machines. There are slight variations in volume in the passages, slight variations in the intake runners, and slight variations in each carb.

To see the magnitude of these combined variations balance the carbs without the YICS tool. Get all the little columns equal.

Now install the tool and start the engine. The variation between the columns is the cumulative effect of the small differences.

You can get close but it won't be spot on without blanking the YICS passages.

 

Injuhneer, some of us been down this road before, some of us agree to disagree, and thats ok too
if you sync with the tool in then remove it the sync changes and the carbs are no longer in sync, but thats ok thats what yamaha said to do.
then there are some of us (i for one) who sync without the tool and ride with the carbs in sync
but i am flexible, maybe i'll try the tool again just for the sake of science

 

On vacuum balancing:
I was really bored, so I inter-connected the vacuum ports on my 750 that -has- YICS. I saw a noticeable improvement at the low end - the bike has more take-off power. Nothing much in the top-end department though. Still, I'm gonna leave it on for a while to see how it affects mileage, etc.

On the YICS tool:
I found that if you have a set of four gauges (dials or sticks, doesn't matter), the YICS tool is more of a nuisance than a helpful tool. I consistently get smoother idle tuning without the tool. When I used 1 or 2 gauges to sync, the YICS tool helped a lot, since I didn't have to switch the gauges back and forth quite so much to see how one adjustment affected another.


...just my 0.46 Rubles (that's 2 cents U.S.)

 

i picked up 3 miles per gallon with this mod all around happy with the difference

 

That reminded me of this:

http://journeytoforever.org/biofuel_lib ... h/me3.html

I saw a web page (some years ago) where someone had modified this idea onto a GS850 Suzuki and was impressed with the results. You could easily connect this through the vaccum hoses on an XJ's carb boots.

 

Any more reports on this? IIRC, mountain sled from teh 90's had something similar done to it from the factory.

 

what does yics stand for?

 

I also connected my vacuum ports together, and i am really happy with the results. Faster starts, no popping at all, good strong acceleration, smooth running engine, awesome modfor under 5 bucks. Great mod. Very happy.

 

A balance chamber on the intake. YICS (Yamaha Induction Control System), a fuel-saving engine system, was developed for 4-stroke engines. (from the Yamaha website)

Yamaha does not make the tool anymore, I bought mine from Mike Oberle, but here is a DIY kit.

http://www.crc2onlinecatalog.com/yics_tool.htm

 

i needed new caps on the vacuum ports, so i tried this mod and to be honest
with you i can see no difference at all but i wonder what it's doing to the petcock vacuum diaphragm, if anything it's going to make sync'ing a little more complicated

 

sorry to refresh an ancient topic but when I read this I had to comment. I'm sure what follows has been said elsewhere.

I read all three pages of this and I'm a little shocked no-one said the word "Vortec" even once, when describing how YICS uses the rush of another cylinder's intake charge abruptly cut off (think water hammer in old plumbing) by a closing intake valve and redirected through the passage to puff a swirly mixing effect into the stream of another cylinder mid breath.

Funky 80's technology? yes. (I have an atari dash Marty McFly would be proud of)
Bassackwards? NO.
YICS was one piece of forward thinking technology, aspects of which are being used in motor design today. The implementation was crude and imperfect yet simple and effective. There are no moving parts. In fact there are no parts at all, just a hole where other motors have more metal. yet it enables these motors to yield a better KW/h to fuel ratio than without.

 

Liquid gasoline does not burn.
Gas vapor mixed with air burns. The carbs mix gas with air, the term "atomized" is used to describe the fine droplets. It takes time to evaporate. Spray Windex in the air, watch the droplets fall for a few seconds. There's 50 intake pulses per second at 6,000 RPM.

If you had all of the air/fuel/droplet charge rotating in the cylinder during the intake and compression stroke (the whole 0.02 Seconds) the fuel droplets would tend to wet out the cylinder walls in the same way a Dyson vacuum cleaner works to separate dust.

In fact, you would want a tumbling charge with multiple vorticies, the fuel droplets being exposed to many changes in direction.

The air/fuel in the YICS system and this particular mod would have the time to fully vaporize, which produces a better burn. This could be the main effect.

When you consider a 32 MM carb being influenced by a 2 MM passage, I'm not sure how much rotation is being created anyway.