carburators XJ 1100 & Throttle Cable

[dodjh]

After installing carburators, what is the starting numbers of turns

on the adjusting screws (3 of them)

[HobbyMan]

you actually can bench snc them on a bench before you put them in. THe other way to do it is to position the tang on each carb half way up/down. THen you use a vacuum snych tool to do the fine adjusting. If you don't have the sync tool, you must bench sync them. its in the tips somewhere. Search for it If this is not what I think it is, oops

[dodjh]

XJ 1100 carburator

Thanks for the reply---You don't have to turn the screws a certain number of turns when you re-install carburators?

dodjh

[HobbyMan]

you are talking about the screws between the carbs aren't you? Those screws are there to adjust the throttle plates on each carb to make sure that the vacuum is equal on each intake. If you have the Yics system there are some more steps involved, but the idea is to get the intake manifold pressure(actually vacuum) equal on all cyls to give a smooth idle and allow the rpm to drop evenly

[HobbyMan]

Bench snycing them consists of a somewhat visual adjustment by placing a bread tie at the bottom of the throttle plates to make sure that each plate is open the same amount. The only way to get them exact(sort of) is to run the engine with a vac snyc tool attached to the intake boots. The yics must be plugged to do this. The difference in vacuum determines the number of turns required
post:998

[dodjh]

carbs XJ

The carburators I put on are newly gone through. I was having a problem with the plugs fouling out because of too much fuel
(rich). So I backed off the turns down to closed and
then opened them up 2 and a half turns and now it want fire off.
It made a back fire like a 45 going off in a garage.
(Those were the screws I was reffering to.

dodjh

[HobbyMan]

then there are 4 screws. not 3. one on each carb.(unless xj is diff.) I set mine about 3.5 turns out. If you are turning the three screws between each carb, that is the wrong screw. THe idle mix screws are on top of each carb. Some people run them more than 3, but I don't know of anyone running less than 3.
POST 1000
Ohh yeah...... All those late nights finnaly.... Ohh whatever never mind

[dodjh]

carburators

Mine is the 82 XJ 1100 YICS---I didn't see any screws on the top unless your talking
about those cavities with factory plugs in them.

dodjh

[HobbyMan]

ahh, you dissapeared. Thems the ones, I think. Those should be your idle fuel setting. usually about 3 turns out.

[mro]

less than 3.

On my 80G, between 1 3/4 and 2 out....

On the XJ,
bench sync
plug YICKS
warm up engine (place fan blowing on it)
vAc sync em
adjust fuel/air screws (may need to remove plug/cap over adjustment screw.

do vac synk agin.
remove plug
test run bike (fun part)


mro

[mro]

Hey HobbyMan .......

You just popped 1000 posts tonight???

Welcome to "guru"vile



mro

[TopCatGr58]

Hey Dodjh,

Okay, there is some confusion here, so pay attention, please!

The 3 screws you have been referring to ARE the butterfly adjusting SYNCHRONIZATION screws ONLY! They are to be set by the Bench Synching technique to barely open the butterflies.

The other screws we are talking about are the PILOT JET screws that are under the brass factory sealing caps on the front top of the carbs, NOT IN BETWEEN the carb bodies.

You need to pull them off, reset the 3 synch screws so that your butterflies are bench synched, all closing at the same time when you actuate the throttle. Then, you will need to get a small drill bit, and drill thru the brass caps, CAREFULLY, you only need to go about 3/16" deep to get thru, don't want to damage the pilot screws underneath! Then, get a sheet metal screw of modest 1" or so length, screw it into the brass cap hole till it grabs, and then use a plier to wiggle and pull the cap out and discard.

And since you may not have had them off during your carb cleaning, you'll want to remove the screws completely, AGAIN be careful cause they have very small washers and rubber washers around the bottom of them that can get lost, and then do a little more cleaning of the Pilot Jet circuit with your carb cleaner spritzing up thru the bottom of the carbs pilot jet so that you can see and verify flow thru the pilot jet screw hole and the 3 holes inside the top of the carb throat close to the engine side of the butterfly!

Now, you can put them back in GENTLY seating them, and then turning them back out the 1.5 or so turns that you've been reading about for the PILOT JET SCREWS!!
T.C.

[81xsproject]

A lot of folks around here also recommend plugging off the YICS (Yamaha Intake Control System???) ports.

[Jerry]

The XJ has a port (tube) cast into the cylinder assembly. This allows the carbs to access a common vacuum source. Shop manual procedure says to block this port with a special tool needed for the job; blocking the ports isolates the carbs so you can get more accurate synchronization.

Do a search on YICS tool and you will find various threads on this topic. In the Tech Tips section under off-site links you will find this link to making your own YICS tool:

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

Another bunch of threads have to do with using the ColorTune tool to set your pilot jet settings. See:

http://www.xs11.com/tips/maintenance/maint34.shtml

Having seen Ken Talbot use this item as last year's Selkirk Mountain Rally I am pretty well convinced there is no better way to set your idle to 4k mix than with this tool.

[trbig]

If you haven't done what TC is talking about (Removing the caps) and everything else on your bike is stock... I personally wouldn't do that.... yet. I am betting that your carbs just need a synchronization. What you do on a bench synch, is get all the carbs set the same... but not every cylinder is going to need the exact same flow (Different compressions and such) So this bench synch gets you close... but not dialed in. I also don't trust someone else to go through the carbs. We hear on here quite a bit how people had them "Professionally done" only to turn around and have to clean them themselves.

A method I found easier than a bread tie for bench synch'ing them, is to look into the throat of your number three carb while it's sitting on the bench. At the bottom of the throat, the butterfly valve will be either very close to, or splitting a small hole on the bottom side. This number 3 carb is non-adjustable, so you adjust the others to it. Move the number 4 to where it matches 3, then number 2 to match 3.. then number 1. If you adjust #1`first, any adjustment to #2 is going to change it. This is reverse of how you synch them with gauges.... which leads us to another thing. I wouldn't do any adjusting on them after re-installation until you get a synchronizing tool. The cost is probably going to be cheaper than having someone else do them for you, and you will more than likely need them again at some point in the future.

So.. now you have a difference of opinions... decide what's best for you.

Tod