Carb Sync Trouble

[rombat]

Trying to sync the carbs on my 1100xj. When I insert the YCIS tool the #2( octy port) vacuum goes way up and will not adjust. Without the blocking tool inserted the vacuum is even between #1 and #2. As I understand it the left screw syncs 1&2, the right screw syncs 3&4, and the center screw syncs the two sides to each other. I have done this bike before without this problem.

[rombat]

I was hoping someone could give me an idea what I am doing wrong. I synced the carbs yesterday, completely forgot to insert the YICS blocking tool. Took me 15 mins, all 4 level. Decided to redo the sycn properly today with the tool in place. As mentioned the #2 vacuum doubled in height (mercury tube) with block inserted. Adjusting the screw between 1&2 made no difference,yet it worked yesterday. I finally gave up. A buddy has a different sync tool that I will borrow someday and try again.

[HalfCentury]

It is possible that one or more of your ports are dirty/blocked. The ports have to be open/clean for the YICS system to work. Get in there with the equivalent of a rifle barrel cleaning rig and some solvent/cleaner.

I have owned an XJ650 and XJ1100 and did carbs and sync on both bikes.

You should ask on xjbikes.com where the YICS is discussed in much detail.

Some owners do not use the blocking tool and some owners do use the blocking tool.

You will know you have proper sync when the bike pulls like a freight train on the road.

[rombat]

Thanks. I brushed it out with a .375 nylon rifle brush before I started and again afterwards thinking the same thing as you, no difference.

[HalfCentury]

How does it run with the blocking tool in place? It should run perfectly fine with blocking tool in place.

[soccer4m]

synch xj

Hi Half century,,,,just a thought,,,I also have an xj1100 and have synched it with the yics blocking tool and without it,,,,it didnt make a difference. It should with the tool in as each carb can be adjusted individually, but I have done with it in and not in and could still adjust the synch. SOOOo, try it without it in and try to synch them, by turning the outer screws for the outer cylinder pairs I can hear them smoothing out and rpm increase when they are synched, then adjust the center screw for a nice smooth sound from the engine. Also maybe one of your gauges is messed up, I had one that died so try switching around the vac tubes to the gauges and see if that makes a difference,,,,go xj...Mike in SUn Diego

[HalfCentury]

My sample size is exactly 2 bikes; an XJ650 and an XJ100. Not enough to make any generalizations about everybody else's XJ bike.

I do not think that the YICS port has a performance effect. I think that the YICS effect is emissions and backfiring (smoothness).

[3Phase]

YICS Tool - Use It

The YICS block-off tool makes a difference synchronizing the carburetors
and adjusting the idle mixture screws:-

Youtube / ThreeFaze / XJ1100 Carburetor Synchronizing ~ 40 seconds


Without the YICS tool before sync and mixture screw adjustment:
All 23 cmHg/hg

With the YICS tool before sync and mixture screw adjustment:
#1 25 cmHg
#2 20 cmHg
#3 17 cmHg
#4 23 cmHg

8 cmHg difference between high and low vacuum

With the YICS tool removed after sync and mixture screw adjustment:
All 20 cmHg

[skids]

The YICS block-off tool makes a difference synchronizing the carburetors
and adjusting the idle mixture screws:-

Youtube / ThreeFaze / XJ1100 Carburetor Synchronizing ~ 40 seconds


Without the YICS tool before sync and mixture screw adjustment:
All 23 cmHg/hg

With the YICS tool before sync and mixture screw adjustment:
#1 25 cmHg
#2 20 cmHg
#3 17 cmHg
#4 23 cmHg

8 cmHg difference between high and low vacuum

With the YICS tool removed after sync and mixture screw adjustment:
All 20 cmHg

So it begs the question: If the carbs are synchronized with the tool, what good is the system? Is it for drifting out of synch???

[3Phase]

So it begs the question: If the carbs are synchronized with the tool, what good is the system? Is it for drifting out of synch???

Unless the throttle shaft or adjuster screws are worn out then you really shouldn't have to fool with the YICS, sync and idle mixture. Once it's dialed in, it shouldn't change until you do something like R&R/clean/rebuild the carbs or change the valve shims.

Obviously, the synch and idle mixture adjustment will change slightly after you replace the cam chain, lap the valves, or hone the cylinders so you'll need the YICS tool to tune as the parts break in. After I reworked the engine in my XJ and took off for the Kremmling rally, I forgot to bring the tool and DiverRay brought his vacuum gauge set. I try to remember to keep it stashed on the frame now so it stays with the bike and there's no drama when I want to use it.

[TopCatGr58]

Hey Skids,

Read all about it here:

http://xj4ever.com/catalog/yics.html

T.C.

[skids]

Hey Skids,

Read all about it here:

http://xj4ever.com/catalog/yics.html

T.C.

Thanks TC, for my info.