UPDATE-yics substitute

[YellowJacket!]

I haven't decided if I am going to keep the copper color, paint them black or silver, or cover them with steel braid...overkill since you won't be able to see them with the tank on.

David

[VisionaryDan]

Dave,

I took an old bicycle tire tube and cut it to length and stretched it around the outside of mine. That way it will stop it from being metal to metal against the frame and it's black.

The copper pipe was a great idea. I used a "T" with a 1/2 fitting in the center. Looks very similar to yours and I mounted off the same frame member as you did except below instead of above. A couple of wire ties around the frame and I was all set.

I hope to have my pics out here tomorrow.? This is a much better solution than trying to fix the old YICS. It's perminate and should never have to fool with again.

Thanks again for the idea,
Dan

[Lucky]

The only thing i question with your YICS is that with the long hose length you now have, you've changed the totall volume dramaticly, i'm wondering at the speed the mixture is pulsing in & out of those hoses, if they are really actually making it all the way to the copper tubes.

Also now that i think about it, with copper being a good conducter for heat transfer, i'm concerned about the possability of the fuel mix condensing in the copper YICS's & returning to a liquid state...

might be a good idea in the future to mount the barb fitting in the end cap, & have the far end higher.

--Lucky

[ProfessorRex]

How long are the stock hoses?

4" of 1/4"id hose is roughly 12cc's

[VisionaryDan]

I'd say that the hoses are about 4" longer than original. Maybe my calculations are wrong but 1/4" dia X 4" long hose comes to 3.2176cc

.125" * 2.54 =0.3175 cm radius

(0.3175 * 0.3175) * PI? = 0.3167 sq cm

4" * 2.54 = 10.16 cm

.3167 *10.16 = 3.2176 cc

I can't believe this is significant enough to cause a problem. But to Lucky's point the chambers get a little warm and the copper will conduct heat much better than the original plastic YICS. On the other hand so will the aluminum bottles that people have been using.

At this point all I know is my bike is running better than it ever has and I'm going to leave the copper YICS on until it causes a problem.... and I'll post any significant issues that come up.

Dan

[ProfessorRex]

You're right, I used the diameter when I should have used the radius!

[YellowJacket!]

Good point about the copper/heat issue.  We'll have to see about that as soon as I can get up and running and with Dans tests.  Length of tubing is a bit longer now at nearly 10 inches.  I used heavy duty braided fuel line hose with 1/4" ID.  It is less compressable than the vacuum hose is and more tolerant of fuel.  From what I read about the YICS, it is combustion gasses that go into the YICS after the burn so the likelyhood of actual unburnt fuel making it there is low.  But, I could be wrong, so use caution.  I can also mount the tubes side by side and place them between the two cylinders to maintain the same length of tube.  My guess it that witht he linger tube, the velocity of the gas leaving the UYICS may slow down and there may be a back pressure created by the gas having to flow up the longer tubes.  Afterall, I'm sure that Yamaha engineers put years of R+D into the YICS to come up with the actual sixe/volume, placement and material.

David

[Lucky]

Close, it's unburned intake mixture that the YICS injects into the cylinder.

[VisionaryDan]

Ok here are the pics for my UYICS. I apologize they're a little fuzzy but I hope you can get the idea.

They are made from 1" copper tubing fixtures and measure 5" long. The volume calculates to 68.5cc and with about 4" extra hose it comes out to about 72cc in volume.

So far the only negative is that I am experiencing a slight stumble about 4000rpm. It only seems noticable when I have a passanger on the back. Otherwise the bike is running great. Temp seems good and it idles smoother? than I ever remember. Acceleration is smooth and consistant through RPMs above 4000.

I'm playing around with the mixture screws to see if I can eliminate the slight stumble.

So far so good.

Dan

[VisionaryDan]

Just to update everyone about my home made copper YICS. It continues to work well but I have run into one issue that I believe is related to what Lucky had brought up as being a possible issue. That is heat that can build up in the copper tubing.

There seems to be very little issue on cool days but on 85+ degree days when waiting at a light or stuck in traffic the bike has a tendency to backfire on accelerating. I believe the mixture gets held in the chamber when idling longer and the mixture heats up causing a misfire.

It's either that or the extended length of hose in conjunction with the copper holding the heat. I may try to mount the chambers closer to the cylinders to see if this makes any difference.

Dan

[VisionaryDan]

If anyone is interested, moving the copper YICS closer resolved most of my backfire problems by about 90%. Still get a pop once in a while when letting off the gas but this only happend a couple of times after ridding it for over an hour.

As far as temp is concerned the chamber gets much hotter being closer to the cylinder. Again I don't know what role that will play in all of this.

I may change the mounting and possibly add cooling fins at a later date.

I'll update this if I do.

Dan

[Junior]

Dan-I copied your design. Due to time constraints,  I just used a 1 1/2 " long hose on each one and they are hanging loose on engine. The copper gets very hot and have not had any backfiring at all. I am running a early model 82 without any carb updates (stock carbs) which could have a lot to do with it. I know that when you start playing with the air-gas mixture on any engine, you can get into a lot of variables. Your design is working great on my particular bike. Bike starts instantly anytime. Probably my dumb luck, as I had no idea what I was getting into when I purchased the Vision. Right now my V looks like is has two large warts hanging off each cyl. (will have to work that out later) but it sure runs great, so I am riding, warts and all.  Junior

[Extent]

1/4" dia X 4" long hose comes to 3.2176cc

Well you will notice that the YICS chamber for the rear cyl. is smaller than the one for the front, by my estimates measuring about, it's about 3.375 cc smaller.  I'ld chalk that up to the difference in the lengths of the vacume lines, but the rear cyl. is the one w/ the shorter lines to begin with.

I recently pulled my ogre snot YICS off and put a repaired half sized YICS on and noticed a defenate improvement.  I'm pretty sure the ogre snot one had larger-than-stock chambers, and they were equal in size.  I'm really beginning to think that it was a lot more carefully designed than I originally thought, and at this point erring ont he side of small seems to be a better bet.  I'ld be interested in knowing what the exact length of the stock tubing was for both chambers, since mine is long gone.

[Junior]

Extent-This is just a guess on my part, but considering the rpm's the V is capable of  and the 4 valve heads ability to transfer a large volume of air and gas when running, the amount of time the YICS has to function on each stroke, the time allowed is miniscule and the shorter the connecting hose, the greater amount of time the YICS has to function.  ???

[silicon_toad2000]

I think there is more vacuum in the manifolds when the rear cylinder intakes. The rear has the smaller jets in the carb doesn't it, so it makes sense that the rear yics chamber would be slightly smaller??