yikes works

[funkamongus]

yikes,, we all know and love/hate it. I had bypassed my yikes to remove any potential probs to get her going,, got her going... decided to "re-build" yikes.. I didnt have it yesterday,, she was ok, a little slow, but, ok.. WITH yikes.. a little faster, easier breathing up to redline, faster down revs. Im a believer. Yikes works, as far as I can tell.

[Kid Jedi]

I don"t think that is a good test.
The bike feels better, because it was designed to work WITH YICS, not with out. if you want a good test, have the bikes tune checked with YICS and get a hp graph, then remove YICS, have the bike Re tuned, and get a new graph. then compare the two. Which i plan to do after i finish the fuel injection, Hell I could make a print out from the injection computer, I can do it with out a dyno

[RadRacer]

If you do that after the FI set-up, then the results will probably be different then with a carb set-up, IMO.  I'd do it now, not after, if you're going to.

[Kid Jedi]

i am going to get a before and after dyno done. so we will have a dyno of my stock vision with and w/o Yics

[Night Vision]

I'll bet, with the yikes, will be better by 1/4hp

one of my Visions runs better with, the other, without...

[Kid Jedi]

I think the yics adds more torque at the low end but takes a bit of hp from the mid range if i had to guess

[Rick G]

That was my observation , when I first installed MAC pipes. With the  stock exhaust it would rev to 11500 with ease. With the MACs it would flatten out at 10,000 , but mid range seemed better. This was on the seat of the pants dyno .

[Jay]

Yes, yes I am...


Huh?

[Kid Jedi]

In an engine, power for nothing is a lie.  like doing a 7 face valve job means that you increase the total volume of the combustion chamber and produce a little more hp, but loose a little mpg. engines are a big balancing act of what you want. I believe that the YICS improves the low velocity power of the engine by swirling the intake gasses, but at the mid range say 1/3 to 3/5 throttle it actually generates too much turbulence causing pockets if gas to remain un-burnt. From 3/5 to full throttle the engine is running so fast that the YICS effect is so slight it is negligible. 


Of course that is my hypothesis, But I have no way to prove it one way or the other at this point.

[Blake]

In an engine, power for nothing is a lie.  like doing a 7 face valve job means that you increase the total volume of the combustion chamber and produce a little more hp, but loose a little mpg.

Please learn why things are actually done before spouting off theories..and more importantly, dismissing other peoples observations as you have done above.  A "7 angle" valve job has nothing to do with increasing the combustion chamber's cc's.  And multi-angle valve jobs have no relation to lost mpg except for the lead foot syndrome associated with it.

[Kid Jedi]

Sorry, It improves the flow and produces slightly more power, but burns a little more gas. but more power = less gas needed so it balances out.  I miss-edited.

Also I had an idea and I shared it. Isn't that what this forum is for? I don't have all the answers, but I want em. that's why I am here.

[motoracer8]

 I use a Serti valve seat cutter, that makes beutiful radised valve seats, and yes they will flow slightly more than angled valve seats all things being equal. The flow bench says this is true. At wide open throttle is the only place it counts, but I doubt you could tell the difference back to back with the seat of the pants method. I have had Vision heads on the flow bench and I could see no difference with the YICS hooked up or not, but the bench produces a steady flow not a pulse, so there may be something going on I cant measure. I can't see how the thing does much as it dose'nt have much volume and everything about it flexes when the engine is running. It would seem to me that the carburettor would see a better vacuum signal without it. I have never had a stock Vision on the dyno mabe I'll hook mine up someday with and without and see if there is a difference and where.

   Ken G.

[Kid Jedi]

A Serdi cutter? What I would give to be left alone with that machine for a few hours...
Here is what the Yamaha manual says about the YICS system:

YICS
To increase fuel economy through more efficient combustion, the engine is equipped with the patented Yamaha
Induction Control System (YICS). In this configuration, the YICS consists of a chamber linked to the intake
manifold by a tube. Upon intake, the vacuum in the manifold creates a vacuum in the chamber; when the
intake valve closes, the chamber draws in some air-fuel mixture. When the intake valve reopens, the mixture
in the chamber shoots back out through the angled tube and into the cylinder, mixing with and swirling the
main intake charge. The swirling charge is then compressed and ignited, burning more completely and producing
more power than that of a conventional engine.

The YICS affects the atomization of the fuel, and since we have a 80MM bore, we can really make use of the tech

by the way, is there a noticeable change in exhaust note with and without YICS?

[motoracer8]

 Yes, I have read the hype, I think the addvertising engineers make promices then the real engineers have to come up with something so they don't all look like they are full of shit. If it was such a great device how come they don't still use it? It must of cost them all of 25 cents to make the damn thing. And like I said earlyer the whole thing flexes so much how can it have much effect.  My Vision is a 83, stock except different cams and alittle bigger intake valves, and the YICS is still installed, I'll run it on the dyno someday and see if it does make a difference. I could care less if my Vision is faster or slower than another one, it seems to run well with no probblems, I just ride it along. I have other motorcycles that are faster and handle beter, but I like the Vision because it is unique.

  Ken G.

[funkamongus]

Im not concerned with dyno results, myself. I want a bike I can start easy, rides smooth, no vac leaks, good gas mileage, good power, no or as few flat spots as possible, doesnt burn or foul plugs, hole pistons, etc..  hahahahahaha.. I dont know whether its better or not, so far, since Ive been getting her to run, she's running her best, yics sealed and installed, flat spot at around 4k.. otherwise,, shes good enough for me!! Ill be going back and forth and experimenting though..

[inanecathode]

All the yics is is an extra large intake plenum. When the intake valve closes there's a big back pressure spike. Most the time it'll just stop right at the valve then start moving again as soon as the intake valve opens. With the yics, some of that back pressure and mixed fuel continues moving backwards and into the yics box, then back out into the chamber after the intake valve opens. At certain rpm this can act like an acoustic super charger (tiny) and match the harmonic pulses of the intake with the harmonic pulse of the air moving in and out of the box.
I could be bothered to go get my two stroke book and copy verbatim what it says about exhaust shape and length but that'd be confusing, off topic, and boring. To me :P

[funkamongus]

lol...... all good brother!! Id like to get into the theory of this stuff one day,, it seems complex and simple all at the same time.. Yet, its over my head, currently..

[Rick G]

Where is Jason Morris when you need him!!!???  He has said repeatedly ,that the YIKS was designed for the four cylinder engine , where it had some benefit. On the Vision its affect was negligible . He has some basis for this but I can't recite it.

[Kid Jedi]

I think the advertising engineers make promises then the real engineers have to come up with something so they don't all look like they are full of shit. If it was such a great device how come they don't still use it?

The first part is very true. wile working at Thermal Technologies LLC. we had to make up a few crazy theorys.

Why don't they use it today? The design of modern engine heads make the YICS system completely unnecessary.

[YellowJacket!]

KidJedi,
I think based on what you quoted from the Yamaha manual and given the time period during which the YICS was used, it may be more of an emission controlled device "burning more cleanly and producing more power".  As you probably well know, if the fuel air mix burns more cleanly then less CO is produced thereby cleaning up the emissions.  As far as producing more power, I feel like it does.  My buke seems to run better with it and much worse when it is not working.

Why isn't it used today?  Well, that goes along with your wanting to put fuel injection on the Vision.  Thats what probably sent the YICS by the way of the dinosaurs.

You have some good ideas and credit goes to you for wanting to make things better.  If I were you, I'd focus on fixing the stator issues first.  you may just earn yuorself a gold plated staror if you solve that "burining" issue first.

David