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Throw Away Your YICS

Started by PeteXS/GS/CB/XZ, October 18, 2010, 05:25:27 PM

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Re-Vision


Hartless

maybe  mine runs better without because i have mac exhaust. plan in doing a slip on conversion. maybe
Ride Hartless or stay home


"strive for perfection , settle for excellence"

Lucky

I have Macs on both Tourer & as of Sunday, Cafe. i haven't (& don't plan to) removed the YICS from Cafe to see how it runs without the YICS, but I know Tourer runs better...
1982/3 XZ550 Touring Vison, Gold on Black

Hartless

yea, i still havnt really worked all the kinks out of mine , im sure once everything is "perfect" it will run better with the yics
Ride Hartless or stay home


"strive for perfection , settle for excellence"

supervision

 New Yama Super Tenere Air box shows pulsing chambers of some sort
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Extent

Those look more like hemholz resonators to me
Rider1>No wonder, the Daytona has very sharp steering and aggressive geometry.  It's a very difficult bike for a new rider.
Rider2>Well it has different geometry now.

Raj1988

my next bill will be FI .. no question abt te

Disclaimer; Late 90-early duc monsters excluded
Rock and Roll Ain't Noise Pollution

zore

I wont deny that the YICS probably offers some benefit as unperceptive as it may be to me.  It just wasn't worth the hassle of trying to fix it a second time and the bike runs good enough with out it. 

I thought someone on the forum was building some.  Is this still the case?
1982 Yamaha XZ550
1995 Ducati M900

injuhneer

#28
I know, I know. This is an old thread. Adding some color to the subject:

YICS has been implemented on many Yamaha engines. The concept is simple. Air (gases) compress and decompress based on pressure, velocity, etc. Multi-carb bikes also benefit from balance tubes (a passage linking the intake tracts together on the engine side). Combine the two principles, tune the cavities (passages, boxes, reservoirs, etc) to charge and discharge (pulse) in response to fluctuations in the intake tract (Mazda did this by linking the intake tracts on their rotary engines) and the result is a "bounce" of the air or air/fuel mix. This bounce when ported to the intake tract produces the "swirl" (retention of fuel in suspension).

This was much simpler to do in the XJ and FJ engines because they were inline designs. I used to make YICS passage tools for the XJ crowd.
Original tool:



My prototype:



Final version:

The tool blocked the passage during carb adjustment/calibration. The passage was unblocked when the tool was removed creating a chamber for balance on the head side as well as the bouncing air/fuel charge.

To get the most out of the original YICS the carbs should be balanced with YICS blocked off then unblocked reconnected. Then the chamber can act as intended rather than just being a balance passage. It seems however that the YICS on the XZ is different in that the chambers are separate? Yeah, that makes sense.

Anyway...

One of the advantages of posting to an older thread like this: How about just 3D printing new YICS boxes? I have a printer and the materials. Might be worth a shot. I'd be willing to test the concept.

HTH!

- Mike O
1982 Yamaha XZ550RJ