YICS Yes or No

Ok, Theory time.

I plan on doing another carb sync soon and am toying with the idea of not using the YICS tool.

I read on Dave Jacksons website that he thinks it is not neccesary and that had me thinking.

Using the tool is essentialy separating the carbs so they can be synced independantly of each other which is fine except for the fact that you take it out to ride the bike.

Now given the reason for the YICS gallery, which is to equalise out the vacuum of each carb, (Eg if one carb is sucking more then it will take air from other carbs) then shouldn't a true carb sync be done without the YICS galleries blocked by the tool :?:


Essentially, by my way of thinking, the carbs should be synced to suit everyday riding rather than having a tool inserted.


Any comments appreciated.

Cheers
HG

 

I could be wrong, but I believe that you will never be able to "sync." them without the tool. If you just hook your manometer up to the intakes, without the tool inserted, all four tubes or meters would show the same vacuum. Thus one or more carbs could be allowing too much air in and running too lean, or vice-versa, not letting in enough air and running too rich. The gallery will make up for some of the unequal pressure between the carbs, but I don't believe it will do very much to ensure a proper mix of fuel and air. I don't think I would be willing to do a sync. this way, only to find out a few hundred miles later that I burned up a piston in one or more of my cylinders. Cheaper by far to make or buy the YICS tool, than to buy a new engine. 8O

 

Dunno - I've read what Dave Jackson wrote several times - he's very experienced and certainly has put some miles on bikes tuned in this way... I'd tend to listen to him more than most people - if I had a YICS bike I'd try it his way and see what it looked like.

The thing is - why would the carbs need balancing IF the YICS passage caused it to perfectly balance the vacuum across the carbs in the first place? I agree with the logic of the first poster - it makes sense to tune the bike the way it will be run - with the YICS ports open.

You can always shove a YICS tool in afterwards to see what it looked like...

I'm not up on my YICS running a non-YICS bike personally.

Cheers,
woot.

 

I've been considering the whole YICS thing for the past few weeks since I got my YICS turbo.

A thought, unrelated to this discussion, but perhaps interesting.

As I understand the YICS gallery, it's basically just a tube that has inlets for each carb. I'm confused by the design of the YICS tool.

Both the original tool as well as the designs for homemade tools are basically a rod with material that blocks the inlets are various points.

Wouldn't it be far simpler to just make a bigger rod. If the diameter of the rod is such that it blocks the inlets, it seems to me it would work fine and be a lot simpler to make. The only guess I have as to why it's designed as it is would be that when tightening the tool, the material is forced to expand to cut off the inlets. I'm not sure if that's necessary.

Thoughts?

Greg

 

geebake, the YICS tool isolates the ports from each other inside the gallery, but does not cut off the vacuum going to each carb.
If you used a bigger rod you would plug off this vacuum to each carb.

 

gotcha, thanks

 

HG - DO NOT, I mean, DO NOT attempt to sync your carbs without a YICS tool if you don't have one. There is the ole 'twist-tie' method - you use a twist tie to sync all four butterfly valves before you put the carbs back on. That's ok for a basic sync - but they'll still be out.

Best to order a professionally made YICS tool from XJMONSTER from my buddy Mike. It's $36+S/H and was the best $36 I ever spent.

Also, go buy a set of carb sticks and a colortuneII set. The money you spend on these three tools is less than taking your bike to a shop and have them do the same thing we all can do ourselves. Plus, there's a tonne of guides on how to sync our carbs.

I've worked on several dozen XJ's myself. First couple of times it took a while, but now I can color-tune and sync my carbs in around 30 minutes.

And you also get to know your bike quite well - check float levels too while your at it...

 

Mr. Fork;
Do you know when Mike might have a new batch of yics tools ready? I ordered mine back in mid- November. Haven't heard anything since then.

 

a question.
if you remove the YICS and tune the carbs with out it., shouldnt it be correct? is it not there to help equalize a slightly unbalanced carb set up?

 

I have all the tools including a homemade YICS tool, but the bike does not run as well as it should even after syncing using the tool. It bogs down when at idle for a few minutes. This is why I'm considering some fine tuning without the tool.

One of the things that worries me is if there is a buildup of carbon blocking one of the galleries as they are only a few millimetres in diameter.

I think it's worth trying even if I don't adjust anything just to see the difference between using the tool and free flow.

To me the only difference will be between idle and WOT where more air is getting sucked through.

Remember the YICS gallery is a sealed unit so it is not adding any air to the system, just equalising the pressures a bit. Eg, If all the carbs have exactly the same pressure then there will be no air flow between the carbs via the YICS gallery. Tuning it with the tool is working on the vacuum of each carb but syncing without may be allowing a better tune to get all four carbs sucking the same.

Just because Yamaha made a $100 tool doesn't mean it's neccesary does it?

Good to see a few different ideas on this one.
Anybody done a comparison with and without the tool?

HG

 

Hired-Goon;
You should get a stiff wire of some sort and clean those little ports out that you refered to. I cleaned mine out when I built my carbs. And they did have carbon build-up. Definitly a good idea!
You kind of have to feel around alittle, (the holes are in the top of the yics bore alittle to the front), and possibly use a long thin screwdriver to get under the wire and push it up into the hole.

Edit:
Sorry I forgot to mention you'll need to make a small 90 deg. bend in the end of the wire.

 

If you think your YICS is clogged - remove your carbs and use a gun-barrel cleaning brush with carb cleaner. If you don't have one, make one from a coat hangar (that's what I did).

Unfortunately, if you don't use a YICS tool, you WILL have a chamber running either too rich or too lean.

HG - have you checked the coils lately? Maybe your coil caps? I had similiar issues you have but two of my plug caps were worn out.

 

Mr.Fork, you can't get to the YICS porting by taking the carbs off.
If I may wander here....
The YICS inlet hole ( about 3/16" dia. ) is at the base of the intake valve running back to the edge of the head. It takes a ninety degree turn to the gallery on the cylinder casting, sealed by an o-ring ( one per intake port ). The holes drilled thru into the gallery are the smallest point of this system, a 5/64 drill bit just fits.
So without taking the head off you would have to try and poke a wire up into them from within the gallery.

 

Here's a pic of the YICS tool that I fabricated. Version #2.
The first time I tried to use this tool(version#1) I had clear fuel hose on it. The hose did not hold up to the heat of the engine. It got hard and shrank up and became loose in the bore sometime during the adjustment. I didn't notice it until I gave up on the adjustment because I couldn't get it to idle properly, it was very irratic. After I found it loose in the bore I realized that was why it would not idle.
I just found this silicon hose that I going to try the next time it warms up enough for me to work in the shed.

 

Ok, Report time.

Did a carb sync without the YICS tool. (couldn't find it). Prior to this tune I checked the YICS galleries were clear with a quick poke with a wire then hooked up a pipe with the air compressor and gently blew in the gallery with the blanking plugs removed. Got good airflow through all four tubes.

Synced quite nicely and then rode every day for a week.
Found the tool and used it to resync again this weekend and rode the bike to work today.

Ran like shit today much the same as when I synced using the tool the last time. Once it warms up it gains around 500-700 revs more than cold idle.

Syncing without the tool gained me 15% more power, smoother idle and only a minor increase in revs (200) when it warms up.

This weekend I'm going back to resyncing without the YICS tool and it's getting tossed.

Basically it runs much better being tuned to riding specs. YICS SUCKS. :wink:


BTW. Checked all the coils and connections and everything is running to spec. Even put a new blade type fuse box in it while I was tinkering.

A quick description of running like shit.
Coughs and splutters taking off at the lights. Feels like flooding.
Riding at 100kmph it starts burbling out the exhaust like it's starving for fuel. EG, that sound that normally has you turning to reserve. Goes away with a right hand twist.
Starting when hot makes it cough and splutter like it;s flooded and takes a few seconds to clear it's throat.

None of these problems were evident in non-YICS tune up.

Cheers
HG

 

I am amazed, my experience was quite the opposite. I wouldn't throw that tool too far away, you might find a blocked port somewhere. Keep plugging. Cheers.

 

Um, why not? All caps don't convince me. I prefer solid reasoning. I tend to think like the O.P., so what is the reasoning for the other side of the coin (using the tool)?

As for the poster who said you wouldn't see an imbalance w/out the tool because the YICS would balance between the carbs - that's hogwash. Try it and you'll see. Even without the YICS tool, a 1/8 turn of the balance screw will throw things way off.

I think it's funny that those who most often say you absolutely NEED to have something are either selling it themselves or know where you can buy one. Insurance agents come to mind. :lol:

 

Hey Oblivian, you got me really wondering now as I have an 82 XJ550 that I jsut re-built the carbs and am getting ready to put them back on the bike. I have been looking around at the YICs tools and they are VERY expensive. The ones from the UK for $36 + S/H looks like a good deal, but from what I have read on this site, they don't seem to show up very fast. I need to get this sync'd and out the door.

So, when you did it without the tool, did each carb show a different reading? I am just curious cause I think I undertand the theory behind this gallery, and was thinking that if you had a partially blocked port, then that could show that that carb has a higher vacuum than it really has. Not saying your wrong mind you as you know more than I do about these things, just curious. If I can sync without that tool, so much the better and my bottom line isn't affected as much.

Any info on what steps you took to do this would be appreciated. I have an expensive carb sync tool, so that is not an issue.

Thanks!

 

First, don't assume I know more than you - I'm trying to figure this all out like you.

For carb balancing, I didn't have a fancy meter - I just did the water in a tube trick: http://www.obairlann.net/~reaper/motorc ... meter.html When the two carbs being tested are blanced the water levels in the two tubes will be the same (assuming they were calibrated that way to start). What I found is that I could show an imbalance between carbs. I'm not saying balancing without the tool is totally accurate - I don't know for sure.

What I was disputing was this statement:

If that were true, turning the balance adjustment screws would have no effect without a YICS tool in place. I observered otherwise.

Finally, as proof that I don't have all of the answers, my bike runs on choke and revs fine off choke, but low idle is not smooth and wll die out. So I wouldn't necessarily model yourself after me. That all said, the bike _is_ running better than it was before I did the balance (without a YICS tool).

I hope you find tha answers you are after.

Quick edit: I missed one of your questions, tazzmann. Yes, without the YICS tool, I got 3 different readings between the different carb sets. 1&2 were a little imbalanced from eachother, but not much (about 1/4" of water). 3&4 were more out of balance (about 4" of water), and 2&3 were WAY off from eachother (about 2' - yes FEET of water difference). I think at one point in my blind ignorance a few years ago I'd mistaken the middle balance adjustment for the idle setting, so it was about 1/2 turn off.

 

Thanks for the clarification Oblivian. I will check with my carb sync tool when I get a chance, if nothing else, just to see if there is a difference or if you need to lay of the sauce. just kidding. Anyway, I am really curious now and I can see by the posting that others are curious as well. I will keep everyone informed of what I find out.

 

Ok, Since I started this thread I'll continue with my conclusions.

I have synced by both methods and found that a sync without the YICS tool the only way to make MY bike rideable.

With the tool I had idle and power problems. I then resynced without the tool and the levels changed dramatically.

My reasoning for this is as follows.

MY bike is very old and tired so the engine is very close to being worn out.
With the tool, the carbs are being set as individual items seperate from each other but that is not going to work if on cylinder is more worn than the other three.

In normal running, if one pot is worn then more friction will generate more heat. More heat in ONE cylinder will mean that air/fuel mixture for that cylinder will change as the engine warms up and air will be drawn from adjacent carbs. This means one cylinder is probably running richer at operating temp and the adjacent two could be running lean.. Using pods can have the same affect as eventually your two outside pods will end up dirtier than the inside ones, thus restricting flow to those two.

By syncing at operating temp WITHOUT the tool you are accepting the mechanical problems of your bike and syncing for optimal running temp performance.

The downside of this is it will not idle cold without 3/4 choke but this is not abnormal or a major problem.

I am NOT saying you should or shouldn't use the tool, I am just putting forward my opinion of what works for MY bike.

If I had access to all the parts you guys do then I'd just rebuild it to get past my tired motor problem, but that is not an option over here.

Be interested in opinions about my observations/theory from some of the more experienced carb syncers out there.

Hope I've explained this in an understandable way. 8O

 

What you said makes sense to me. I have been really curious about this YICS system. It seems, to me anyway and correct me if I am wrong, that by using the YICS system you CAN avoid syncing the carbs as OFTEN as it distributes the vacuum more evenly to account for a carb running a little rich or lean. However, it also seems (to me) that you WOULD want to sync the carbs up individually to account for the reasons you stated. Syncing and, more importantly, tuning each carb to the cylinder is the BEST way to get the correct air/fuel mixture. In the YICS system, you can't "properly" tune/sync a carb without shutting off the gallery.

Now with all that being said, it also seems to me that by having the YICS gallery, and shutting off each individual carb to tune, you are not truly representing the riding conditions of the bike, so as soon as you finish syncing with the carb tool and start to ride, the pressure differential has changed. In other words, you sync the carb which changes the vacuum property of THAT carb to the cylinder. You take the tool out and the vacuum ends up diverted through the gallery somewhat. Now multiply that by four and possibly a slightly clogged port, worn cylinder rings, etc. You have changed the dynamics of the air flow.

Anyway, I am not pretending to know everything about the YICS system cause I don't. I am just looking at it from a theoretical viewpoint from everything that I have heard and read. This is just my .02 cents and everyone should make their own decision. I just think this is an interesting topic and system.

 

The YICS passage acts as a balance tube and to agitate intake mixture at low speed. The result is less pulsation and better mixture at low speed for smoother idle.

It has very little effect above idle.

Also, consider this: The YICS passages are small and can become blocked (varnishing or coking from the fuel, additives, etc). If you balance the carb without the tool and have a blocked passage the off-idle behavior and return to idle will not be smooth. The motor will tend to lope/surge because the carb(s) affected by the blocked port will have a greater throttle plate opening than carbs sharing a clean passage.

I also recommend that a bottle of Nitro 9 gun cleaner and a .45 cal brush be used to clean the passage at each tune-up.

 

Does your homemade tool have the seal between the washer/flange and the head ?

If it doesn't then one of the small passages is being provided air. That leans out one carb and gives a false vacuum reading.

 

You can get to the small porets if you know where to look.

The better access if from the YICS passage itself.

 

This is because the outside seal is missing from the tool you made. Depending on which side of the motor you insert the tool either your #1 or #4 carb is way out of sync.

They will also be a bit lean and cause the warm idle creep you mentioned.

 

Your conclusions are based on a tool that is missing the primary seal between the tool and passage itself.

 

Sorry, Injuhneer, but I do have a seal on there. A nice thivk rubber washer keeps it tight. Also blew out all the yics passages with air before I did anything. She's sealed tight and flowing freely.

Also blew some air in thru the vacuum ports with the tool inserted to make sure it was sealing correctly. Did it with the carbs off and valves closed to pressirize a clyinder. No air out the other manifolds means tight seal.

I have tryed everything including new intake gaskets to make sure everything is sealed tight. YICS tool does not work for my bike.

There are plenty of other reasons for different vacuum settings like valve clearances etc but at the end of the day my bike runs much better after a sync without using the tool. Full power thru the gears at any revs and a smooth idle. Using the tool makes the bike almost unrideable. Runs like a bomb and gets too hot indicating a lean condition.

I'll stick without till I can source all the parts for an engine rebuild, then I'l do it all over again.

 

Sounds like you have done due diligence.

If I were a betting man I'd bet on leaking throttle shaft seals or plugged YICS ports. There are, as you indicated, other possibilities but you seem to have ruled out most.

Good luck with it.

 

For all of you that are arguing about this, Injuhneer came pretty close to nailing it on the head.

This "amazing" YICS is very old technology, starting from small 2 strokes back in the 60s. Ever heard of a boost bottle? Well thats what YICS is. An inefficient boost bottle (to a point, though on 2 strokes it works because the small engines dont have intake vavles). I made a "YICS" for my 86 and 88 kawasaki jetskis. Yea it really does help smooth out idle and increase throttle responce from idle but thats it.

Tune with or without it, above 1200 RPMS it doesnt matter.

For a good read.... http://eindiancompanies.com/images/resonator.htm

 

I By no means do I claim to be an expert on the subject of the YICS port or carbs but it sounds like it is a leaking throttle shaft seals. Injuhneer seems to know what he is talking about just check out his break system on his XJ900 and other projects. You may want to dump the original Hitachi carbs and fit a set of newer Mikuni’s or Keihin’s. I believe after 1983 Yamaha stopped using Hitachi’s and started using Mikuni’s but not 100 percent if this is true. I was talking to the mechanic at my local bike shop, who is taking out some rusted in bolts in the engine block another story, and I ask him what he thought were the weak spots for the xj750. He said the Hitach carbs and said that the Honda CB750 Mikuni’s or Kawasaki carbs are the way to go. I can’t recall what the kind of Kawasaki carbs he was talking about but I’ll ask the next time I am there.

 

The Kawasaki carbs are probably the Keihen CV carbs. The XJ550 i got is running Mikuni carbs.

 

I didn't hear anyone arguing, did you? Gotta get new batteries for my hearing aid.

 

I will concede the possibility of butterfly shaft seals as I have only replaced the outside two. This was done early on as one side was missing the clip and seal altogether. The one I did remove and replace was still in good condition but definately old.

Again, that's on the list for the full rebuild. Got a full set sitting in the draw here at work.

And yes, the 550's as far as I know all run Mikuni's.

 

Can you give more information on "where to look" other than the YICS passage itself?

 

HG, i think the aftermarket pipes are causing some odd readings in the YICS, as i think it was designed for stock systems only. I could be out to lunch, but just a thought. also good to know I don't actually need one in a pinch.

 

The exhaust system (what I assume you mean by pipes) is not connected to the YICS passage on the intake side.

If you have a good ear for mechanical sounds and have adjusted multi-carb setups you can get the sync close without the tool.

 

Just wanted to throw another wrench into this tangled web...

(How's that for mixed metaphors!)

My XS400RJ has a YICS engine, but the YICS passageways are cast into the head, and not accessible from outside to block with any kind of tool.

The service manual does not even mention the YICS system in its instructions for synching the carbs. You just hook up the tubes and read the vacuum.

Herb

 

On the 400 there are only two carbs. The effect on sync is minimized with only two carbs.