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YICS observation

Started by Coil Coyle, January 27, 2009, 06:21:20 AM

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Coil Coyle

Note: no steel was melted with jet fuel in this experiment.

;D ;D ;D ;D ;D ;D

Well, the Flying Pig needed a shim check and I stripped off the cam covers. I didn't have a shim tool so I was just taking my time pulling the parts to get to the shims. When I puled the YICS bottles off of the engine I did the suck test, (YICS always leak, right?), and sure enough there was leakage between the atmosphere and every hose I sucked.

The next observation I made was that each tube connection to the YICS chambers had an orifice in it's center, my eye says between 40 and 50 thousandths of an inch.

I conclude that, on the Venture, the YICS bottles act as a pneumatic shock absorber or equal a capacitor in a resonant electronic circuit. Energy is dissipated from pressure surges in the intake ports with this setup.

I don't see any point in this bull, I'm capping them off.


;D
$0.02
Coil

Almost forgot; I built a tool from some 7/16 stainless keystock and Lucky's drawing from his website. I pushed modeling clay into the lifter gap to get the width measurement because the Venture has smaller lifters to go with the smaller valves. I used acetylene and oxygen to heat the stock and formed it around a 22mm nut, then shaped it without the center guide ridge on a stationary belt sander. You have to align it carefully but it was a quick job. I'll post pictures of the next try, for a Vision.

hoverhead47

Hi,
You wouldn't believe how long it's taken reading though all the messages to find someone that understands the YICS as I have come to.
Quote from: Coil Coyle on January 27, 2009, 06:21:20 AM
I conclude that, on the Venture, the YICS bottles act as a pneumatic shock absorber or equal a capacitor in a resonant electronic circuit. Energy is dissipated from pressure surges in the intake ports with this setup.

I don't see any point in this bull, I'm capping them off.
;D
$0.02
But it seems that most everyone has missed what this device does for the air flow through the Carburettors.
It seems to me that the prime purpose is to maintain as constant pulse reduced airflow through the throats as possible. 
I seem to recall that due to the very short distance between carbies and inlet valves on motor cycle engines the pulsing of the airflow through he carburettor is more severe than in cars of example.  The manifolds on car engines have sufficient volume in them to smooth out the intake pulsations and that they have optimum rpm ranges.
Some said that the YICS was only to stop the spitting back through the carb and I would say yes but that is not the only reason.
Some have talked about the pressure build up within the YICS.  Really?  Has anyone attached a vacuum gauge and measured it?  Surely it is more about how high (or low) the vacuum goes (unless you're supercharging somehow.  Then you would need a pressure gauge!).

Yes I know this is an old subject but I'm new here and catching up.



The Prophet of Doom

Have a look at some of the patents around that era - there are dozens that talk about methods for inducing swirl inside the cylinder for better burning. 
This is what Yamaha has to say about it... source: http://transgarp.dyndns.org/motorcycle/pdf/History_Yamaha.pdf


YICS (Yamaha Induction Control System)
—Increased combustion efficiency

SUMMARY
This 4-stroke engine system induces a swift swirl of the air/fuel mixture into the cylinder during an intake
stroke so that the combustion speed and effect is increased, thus resulting in an increase in fuel efficiency.
BACKGROUND
This outstanding engine system was developed as a part of Yamaha's positive answer to the worldwide
problems of protection of resources and energy conservation. Its construction is so simple that it can be
adopted in any kind of 4-stroke gasoline engine, regardless of the number of cylinders and cylinder shape,
with only minor modifications in its design.
OPERATION
• Use on a multi-cylinder motorcycle engine:
The YICS includes a sub-intake port along with each main intake port. The sub-intake port is about one
fourth the size of the main intake port. The nozzle of each sub-intake passage is set parallel with a tangent
line on the cylinder. All these sub-intake ports are designed to work in linkage with one another.
When the intake valve on a cylinder opens, all the others are kept closed. Then all the air/fuel mixture in the
interrupted narrow sub-intake passages rushes into the opened sub-intake port, thus producing a swift swirl
when it goes into the cylinder. Compression, ignition and burning take place while the air/fuel mixture is
still swirling along the inner wall of the cylinder. This results in the same level of combustion effect as a
good conventional engine, despite much less fuel consumption.
RESULTS
Fuel efficiency is greatly improved.

hoverhead47

"a separate chamber on each side so that air/fuel mixture is compressed into the chamber by utilizing the
induction momentum during compression stroke. The passage leading to the chamber is smaller in diameter,
and the compressed air/fuel mixture is made into a jet stream by utilizing the negative pressure during
induction stroke."

"The air/fuel mixture fills the cylinder quickly, which in turn shortens the period of combustion time, thus,
increasing power output and reducing fuel consumption"

"This system utilizes the negative pressure produced in the intake passage when the piston moves up and
down to induce a part of the air/fuel mixture into and out of a special chamber. In this way the fluctuations
in the velocity of air/fuel mixture stream can be evened out, thus creating a more stable and effective intake
function for higher power and better fuel economy"

Aren't all these statements true? 
Surely keeping the the air/fuel flow steady is what it's about because swirl in the combustion chamber can be induced by all kinds of other devices.
Would be interesting to see what the technical papers said rather than the promotional blurbs.





The Prophet of Doom

I've read through a lot of the patents of the era (all available by searching Google).  Keeping air/fuel flow steady I did not see mentioned; that doesn't mean it doesn't happen (as it obviously does), just that in fuel crisis / emissions mad 70s & 80s, it probably wasn't the prime motivation.

The idea of swirl improving burn efficiency was well established by the mid 1970s, and there are many dozens of ways explored from tiny vanes in the intake tract, through to shaped heads and spinning vortex generators. 

Yamaha would have had to come up with their own ways to avoid paying royalties. 


skucera

Thank you for reprinting this patent.  It really explains how YICS is supposed to work.  Now that I have a mental picture of how it works, I'll be able to see if my YICS was disconnected for any functional reason, or just out of anti-smog paranoia.  (I can sort of understand it, because most things hung on engines in the Seventies and early Eighties sucked power away and had to be exorcised.  YICS is unique in not sucking power, but instead in boosting efficiency.)

Scott

The Prophet of Doom

Skucera, most YICS are disconnected because they are no longer sealed.  They were particularly poorly manufactured and once the adhesive fully dries out leak like colanders.  I've not seen one in the last 15 years that doesn't need sealing up.  I've even had one explode which gave me a bit of a fright.

You can tell if it is sealed by blowing into each hose while under water - you should get no bubbles around the join, or out the other hole.  A leaking YICS is far far worse than blocked off YICS ports, and probably the single most common cause of a poorly running XZ, next to a stuffed R/R and/or Stator.

BTW that reprint was from Yamaha's History of Technology - not a patent

If you don't believe they work, tune the bike for the YICS, then squeeze the hoses shut - your RPM will fall dramatically (for the same amount of fuel)

fret not

Maybe it's time to make a good substitute for the leaky bits.  I think I have a graduated cylinder somewhere to measure the volume of the chambers and connecting tubes.
Retired, on the downhill slide. . . . . . . . still feels like going uphill!

The Prophet of Doom

Good idea Fret nut.  I like these once here from Boost Bottle Industries.  A little spendy, but would look great

http://www.boostbottleindustries.com/Boost_Bottle_Industries_Home.html

I think for 2 strokes the bottle capacity is the same as the engine capacity, but they will custom make to any size

Tiger

Hmmmmmm, the old Yikes problem lol...

Over many years, this little triangle has caused a great deal of line space here on the ROV...some folks are FOR and some AGAINST this wee gizmo.

When it was brand new & first introduced on the Vision/XZ550RJ/RK..and you can argue the whys and were fores until your blue in the face for it's installation...it was great, mmmm sort of.

Some people point to better starting, running and fuel economy with it installed and functioning properly...PROPERLY...and there is where the problem lays. Years of hot/cold/hot/cold/hot/cold, etc, etc, (more cold than hot!!!), this wee plastic box starts to leak and we all know what that means!!!

On 'The Mistress' I had no starting or running issues without it...and fuel economy was never an issue for me...

Me?? I think this is a weak link in the Vision and have discarded every single one, on all the Vision's that I put back on the road...and you could never convince me other wise ;)

Hospital clean and synced carbs, with the two YIC's ports sealed off will give you a great base line/starting point, to a well running Vision 8)

Keep up the good work boys and girlies... :angel:

                               8) ....... TIGER .......  8)
Life should NOT be a journey to the grave with the intention of arriving safely in an attractive and well-preserved body, but rather to skid in sideways, body thoroughly used up, totally worn out and screaming HOOOOYA lets go again baby !!!!!!

'82 Vision, Pearl Orange finish, lots of up-grades!!!

hoverhead47

Well my latest observation is that mine is leaking between the chambers.  I either look for the donor bike one, hopefully it's ok or I'm looking a some remediation work.  As for leaving it off, I think that the engineers would have researched and tested extensively to have worked it out reasonably well.  I think I'll be keeping it on.

Rikugun

Quote from: hoverhead47 on October 03, 2014, 10:08:03 AM
As for leaving it off, I think that the engineers would have researched and tested extensively to have worked it out reasonably well. 

No offense to engineers but that statement has been proven wrong too many times for me to agree with it.  :)

I've read many, many posts about the YICS. Each has their pet theory on it's purpose, operation, relative value, ideal material, volume, etc., etc. It's interesting that those who champion the YICS feel they are in good company and in the majority while the naysayers claim the same.

Quote from: fret nut on October 03, 2014, 01:05:37 AM
Maybe it's time to make a good substitute for the leaky bits.  I think I have a graduated cylinder somewhere to measure the volume of the chambers and connecting tubes.
I think this has been done by several members. A search would yield lots of hits - with no consensus I'm guessing.... ;)
It is far better to grasp the universe as it really is then to persist in delusion, however satisfying or reassuring.  Carl Sagan

jefferson

A friend here has measured the volume and made some replacements out of copper tubing and mounted them horizontal on the frame rails that run beside the engine. His hoses are longer so I'm not sure if he took that into the equation. I really like that boost bottle thing. Just need a good mount for them.

The Prophet of Doom

Boost Bottle Mounts are available on ebay
http://www.ebay.com/itm/Dual-Boost-Induction-Bottle-Mounts-Set-of-4-RC-CAR-Truck-or-Boat-/261614157149?pt=Radio_Control_Parts_Accessories&hash=item3ce96b3d5d

Searching for these, I found dozens of different boost bottles - worth having a shop around

skucera

Quote from: ProphetOfDoom on October 03, 2014, 12:49:32 AM
You can tell if it is sealed by blowing into each hose while under water - you should get no bubbles around the join, or out the other hole.  A leaking YICS is far far worse than blocked off YICS ports, and probably the single most common cause of a poorly running XZ, next to a stuffed R/R and/or Stator.

That's a neat idea.  I've got to try it.  It's such a simple test.

Yes, I've been reading all the debate, running back for years, about YICS.  I've got to think that the Yamaha engineers who came up with it and who integrated it into almost every engine they designed for years, that their testing must have been unequivocal.  Now, maintenance issues are clearly an issue, but I'm an engineer, and I think I'm up to figuring out how to fix it if mine is fubared.

Scott

The Prophet of Doom

I did a quick measure with my measuring spoons I use for cooking.  Not very accurate but seems like about 85ml (cc) Front / 90ml (cc) Rear.  I'm sure someone can do a more accurate job than that though.

Given the design of the YICS near the ports it really does look like the difference is purposeful.


fret not

After mulling this "technological advancement" over for a while I wonder if the big Y was just putting one over on the California Air Resources Board.  It LOOKS like it MIGHT work, but so far no one has clearly demonstrated that it does what it claims to do.  Yeah, there have been dyno tests (?) with claimed results, but just telling a bureaucracy that it does and producing piles of documentation and engineering papers (sufficient to thoroughly confuse most folks) TA DAA!  The emperor's new clothes! and no individual bureaucrat is going to speak up against the brilliant technological superiority of the Japanese engineers and risk his (her) career by looking the fool that doesn't understand it all.

The California Air Resources Board (CARB) was behind the "California vehicles" and "49 state vehicles" that manufacturers had to make for many years until many other states agreed to accept the California spec vehicles.  All this in the quest for cleaner burning internal combustion engines. 

Nah, Yamaha wouldn't do something like that.  Never mind. ;)
Retired, on the downhill slide. . . . . . . . still feels like going uphill!

jefferson

Did you include the hoses in your measurements? If I remember right the length of the hoses are different and the longer hose may go to the front cyl. with the smaller volume and they may equalize out.

supervision

 When I made mine out of small wd40 cans, the back cylinder is a short hook up. The front uses a copper tubing to make the bend under the throttle linkage and then is zip tied to the frame.  I leave it hooked while adjusting the carb
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The Prophet of Doom

Quote from: jefferson on October 07, 2014, 09:54:36 AM
Did you include the hoses in your measurements? If I remember right the length of the hoses are different and the longer hose may go to the front cyl. with the smaller volume and they may equalize out.
I excluded the hosework, but included the little stick out bits.  5ml extra for the longer hose sounds about right.  Good thinking.

I'm not so sure that I like the look of a couple of WD40 cans hanging off the side of the bike.  Perhaps something a bit shinyer?