Carb synchronizing on a yics xj650

I know a guy who claims to be a state licensed motorcycle mechanic. He told me that the yics tool that plugs the holes when synchronizing the carbs isn't really needed. He claims to have had good success without it.

He sync'ed my xj650 without it and it seems to run ok. But, I wonder if it would run better if he had used the tool.
Any thoughts on this and what do the holes that the tool plug do anyway?

 

YICS are series of INTERCONNECTED "auxiliary" intake passages that feed into the intake ports just upstream of the valve head. When one intake valve is open, the YICS ports feed additional intake 'charge' from the intake tracts of the cylinders whose valves are closed to effectively boost and swirl the incoming mixture. You use the YICS tool to block off these passages so that you are reading the vacuum from only the cylinder you are tuning, not from that cylinder PLUS the whole YICS tract (including the 3 other cylinders' intake tracts.) You will get more accurate synchronization with the tool in place which is why Yamaha calls for it as part of the vacuum synch process.

 

And where can this mythical tool be acquired, Master Wizard Fitz? I hope it's cheap because the average Joe will probably only need it once.
I'm thinkin' it's just a shaft to fill YICS channel.

 

Three guesses and the first two don't count... PM chacal or email him: info @ xj4ever.com (take out spaces around the "@" sign.) Yes it's KIND OF just a tool to fill the channel, but it turns/locks to block the passages. If the average Joe plans to properly "care and feed" his XJ he will need it once a season, or at least every other season. There are home-made variations on the official "tool" but if improperly constructed FAIL and can leave debris behind.

 

Proto.....of course, I do carry this tool! It's the YICS Port Blanking Tool part HCP93 for $ 39.95 plus shipping. Here's some other info on the YICS and Colortune plugs:


1) although the Yammy manual didn't specify using a colortune, that may be because it specified using a gas spectrum analyzer for fine-tuing, which of course most of don't have access to----so a colortune is the next best thing (perhaps/maybe/probably better than "by ear", at least for most people). Perhaps the colortune plug wasn't even readily available (or known to Yamaha) at that point in history. Or maybe an OEM like Yamaha felt it had to rely on only the absolutely most precise method of tuning generally available to them---pesky federal regs and all that---and therefore determined that the absolutely best way was an analysis of exhaust gas products (which is probably true, since Yamaha was specifying a method of tuning for Lowest Emissions within an acceptable range of performance, rather than for Best Performance within an unknown range of emissions---although I realize there is a certain overlap in those goals).

2) The YICS port blanking (or "isolation") tool is necessary for getting a better "fine-tune". It allows the isolation of each cylinder/carb unit from all the others, therefore allowing a precise setting of each unit individually, without the influence of other carb/cylinder units to "balance" the weaker or stronger units. Note that the purpose of the YICS system is NOT to "balance" the carb systems, although it supposedly does function in that manner anyway, whether by design or not.

Ideally, we want each cylinder/carb unit to be both equal to all the others in term of efficiency and effectiveness RELATIVE TO THE OTHERS. This allows each unit to pull an equal amount of weight in the engine---important for both engine longevity, efficiency, and performance (both output performance and emissions performance).

Doing so means "tuning down" certain units to match the "lowest common denominator" carb/cylinder unit.

3) Now that each unit is working equally hard, the removal and "balance" achieved by the YICS passage allows for operating variations to be better controlled than by NOT HAVING THE BALANCING EFFECT OF THAT PASSAGE. Under the variety of operating conditions, situations, and loads that an engine experiences...and thus what each INDIVIDUAL cylinder "sees"....it is useful to minimize the effect of such variances on the overall engine, and thus one of the effects of the YICS chamber.

4) Interestingly, Yamaha states only the following about the YCIS system in their marketing materials. Note that there is no reference to emissions or to carb synchronization, etc......it's merely a performance enhancement feature that has nothing to do with better performance via a "balanced" intake system:

"...the Yamaha Induction Control System (YICS) adds power in the low to mid-range and delivers about a 10-percent increase in fuel efficiency. YICS is a secondary port cast into the cylinder head, linking the main induction tracts. It brings the secondary charge into the main tract at an angle so that it mixes with the main flow of fuel and the mixture is swirled completely around the combustion chamber, thus resulting in more complete cylinder filling, which leads to more power and less fuel consumption."

5) I'm not real sure what Yamaha means when they say a "secondary charge"......or if there really is such a thing, other than the intake of air created by this YICS passageway.

From reading the above Yamaha explanation, it seems that the motivations of the engineers were to create this "secondary charge" and inject it into the main intake flow at an angle (to create additional "swirl" and cylinder-fiiling potential), and YICS is how they went about doing so. The "balance" issue was secondary (or perhaps not even a consideration or an issue, good or bad), and the YICS tool was now needed to do a "proper synch"....each unit working equally hard (same as in the "old days" before a YICS passage existed)......

 

That's EXACTLY what they mean; the "secondary charge" consists of intake air from the three other cylinders that is effectively "waiting" in the ports (and in the YICS chamber) for their valves to open. YICS diverts some of that to the cyl whose valve IS open.

Precisely. That was their intent, and they succeeded. What they DIDN'T do was reveal their true "motivation" which was a cleaner burning engine that didn't sacrifice performance in the pursuit of said cleanliness. I think the fact that the YICS motor was a BETTER performer was an unintended side effect of their true quest, to sneak in under ever-tightening clean air standards especially in California, their biggest market at the time, without having to resort to catalytic converters.

 

Yeah, it was an origional idea and it worked. Of course that's just a baby step, compaired to the design evolution of Yamaha sport bikes.
Hey, I just was out in the garage and I opened up the YICS cap bolt. I happened to have a 3/8in. wooden dowel rod, so I pushed that in. It fit like an 18 year old goddess.

 

Yes, it does, but if there's any "air gap" at all betyween the wooden dowel and the passage, then a vacuum "signal" will also be present, and it's that signal between the various YICS intake passages (one for each cylinder) that needs to be blocked off (completely) in order for the individual cylinder vacuum readings to be "pure". Otherwise, the vacuum signal reading for an individual cylinder will be "polluted or diluted" by the vacuum sginal from the other cylinder(s).

Of course, what your mamometer (<<<--- fancy word for a vacuum gauge, no matter what style/type you may use) is reading is the vacuum signal, and to do a proper measurement of the strength of each individual cylinder ("strength" being a synonym for a cylinder's power output, which is measured by the vacuum pull of a cylinder), you must be reading the vacuum signal from that cylinder and that cylinder ONLY.

The original (and repro) YICS tool has three small high-temp rubber seals that "swell" up when the tool is engaged, after it's put into the YICS chamber. These swollen seals create an air-tight seal between the different YICS cylinder intake passage, thus truly isolating one cylinder from another, as far as their (otherwise) shared vacuum signals are concerned. The YICS tool itself also fits into the YICS chamber rather "snug" even in it's un-engaged state; it's only when its engagement lever handle is operated that the seals swell outward, and create that air/vacuum-tight seal. Once the lever is engaged, you can't pull that tool out of that chamber even with all the king's horses, and all the king's men tugging on it! THAT'S a true vacuum-blocking seal, and that's what's really needed in order to truly measure the vacuum draw of each cylinder and ONLY of each cylinder, individually, without any "contribution" from any other cylinder.

 

I had mine to a licensed mech at a bike shop to get my safety inspection and asked the the guy if he had a yics tool to synch with.He looked at me like I was crazy when I explained what it was,and when I told him I had heard about it at this site he told me that you can't believe everything you read on the internet.First and last time he will ever touch my bike.

 

here we go again
i made one from plans on the internet, put it in did all the right things
everything balanced out perfect
pulled the tool out, capped the ports, started it up and things weren't
so smooth any more
put the gauges back on, balanced it all back up without the tool and never used it again
there's only one way to be sure, try it yourself and see
i still have the tool if someone wants it

 

I suspect you didn't get a good seal on all 4 with your homemade tool.


chacal is right, there is a reason and a need for a proper YICS tool if you are to get these things 100%. I THOUGHT my '81 550 was a great running bike, until I adjusted the valves and got the carbs tuned in; it was a great running bike---now it absolutely ROCKS! The guys here know their stuff; they don't give advice just to watch you go search for a left-handed monkey wrench. I had been working on bikes for over 43 years, but got brought up short by my first XJ. Thanks to all of the experienced folks here (especially chacal, Rick, Bill, Robert, Wiz to name a few) I have a brand-new 27 year old bike and another in the works. Plus a whole new knowledge base of all sorts of cool things I learned here and can apply elsewhere... Do it right, or you'll keep doing it until you do...

 

There used to be a link on this site to a "homemade" YICS tool that wasn't designed properly; it does not have the large end seal necessary to seal off the tool where it enters the YICS chamber. Without that seal, you will have an air (vacuum) leak for that end cylinder (either #1 or #4 cylinder, depending on which side of the motor you inserted the tool into the YICS chamber).

Here is that link. If you try to duplicate the tool using the diagram provided, just realize that you need to add a large rubber seal on the "inside" of what is called the large "fender washer" shown in the diagram. I'm not sure that all the dimensions shown in the diagram are correct, but I AM sure that the lack of that end seal is a big problem!

http://home.westman.wave.ca/~jbe/YICS.htm

 

This post verges on obscene.
:lol: :lol: :lol:

 

I'm surprised nobody mentioned the "oily rag" method of blocking the YICS. Until I build the tool someday, I'll just keep using rags.

I sync with my home made 4 tube manometer.

 

They're also available in flavored versions, or with raised "tickler" ribs for better, more long-lasting performance.