carburators XJ 1100 & Throttle Cable

[dodjh]

XJ carburators

The brass caps on top of the 4 carbs have already been removed-
possibly during the go through process.

If I understand each of you correctlly I need to pull the set
back off and bench synchronize each to # 3. That explains
why the 3 screws were different amount of turns when
I turned them back in.

Looking back on all that you have said and what I have run into,
the Yamaha dealer had already done all of this and I've un-done
what was accomplished there.

The only reason I had to make an adjustment was after idling
for a few minutues, the plugs had black soot on them and had to
be removed and cleaned for the bike to start again.

I haven't been able to ride the bike yet. I made the synchonization out of PVC.
tool with PVC and aqarium valve.

[HobbyMan]

you guys said what I was trying to say at one in the morning...

[Ken Talbot]

It sounds like your dealer may have sync'd the carbs, but did not do anything to determine if they were running rich or lean or somewhere in between. You need to get them back in sync first, and get the pilot screws set to optimum. Then you can go back to checking plug colour at various operating speeds. If you are rich all over, you may need to start with resetting the floats and go through the cycle again.

As suggested, a snyc tool is a good investment that will probably pay itself back with your firt use. Work through this step by step, only changing one thing at a time. The results are worth it.

Be prepared to become very proficient with removing and reinstalling your carb bank!

[trbig]

I might also add... that while at JUSt idle, all of these bikes will blacken the plugs. Maybe not so much that it fouls them beyond use, but these air cooled motors weren't designed to just sit and idle. It does sound like you're running really rich if it does foul the plugs, but I wouldn't judge the plug color too much until you run it up at highway speeds. (If you're far along enough for this bike to do so... you never said.. AND.. We all love pictures!! lol)
Remember that these bikes tend to run better on the SLIGHTLY rich side, so err on that side if possible. Rich blackens things up... lean BURNS and MELTS things up!

Good Luck.


Tod

[dodjh]

XJ carburator

Thanks for helping me out, everybody I talk to here doesn't want
to "work on old bikes." So I will remove the carbs. and set the sync'd by a bread tie or till slightly split hole at butterfly opening-
then how do I set the pilot screws to optimum?

I didn't want those pilot screw openings to be open but
they are and I'll have to deal with them. When I first put the carbs on the bike it fired right up but after all the coughing and hitting on this cylinder and that it would reve up fine. I don't
know what made me check the plugs but I did and noticed how
rich the fuel mixture was.

So at this point I don't know how to deal with the pilot screws
because the factory sevice manual said they were adjusted
at the factory and "don't fool with them." Of course that is water under the bridge now.

dodjh

[TopCatGr58]

Hey again Dodjh,

One thing that stuck out in your recent replies is that the carbs were gone thru at the local Yamaha Dealer! Question is, what did they use for parts, specifically the pilot jets. Did they put the OEM ones back in, or did they acquire new jets? And did they get OEM ones from Yamaha, or did they get aftermarket ones? K&L jet kits are known to have the incorrect sizes in the pilot jets.

These incorrect jets are known to be too rich.

Secondly, the bench synch holes the butterfly almost covers is actually on the top of the carb throat, bottom IF you are looking at them upside down. The #3 carb IS adjustable, thru the MAIN Idle adjusting screw, so you can actually close it or almost close it before adjusting the others to it. Then using the homemade YICS Tool (see tech tips on how) you can vacuum synch them with your synch tool....you said you made one with PVC pipe and aquarium valve...didn't mention the vacuum gauge?

As for the optimum pilot screw setting, again using the YICS tool, you can first set them to 1.5 turns out from gentle seat, then since you probably don't have a colortune device, you can use Ken Talbot's Auditory technique for setting them, I'm pretty sure I added that as a tech tip as well. Browse the tech tips from the MAIN FORUM PAGE, scrolling down, not just the link in the left yellow column!

BTW, are you running the OEM airbox, or are you running Individual filters?? Is your filter clean, new? ALso, is your snorkel under the seat open, not crimped, bent or restricted.
T.C.

[dodjh]

XJ carburator

I don't know the answer to the first paragraph questions--I hope
they used OEM parts.

I do have a vaccum guage set up on my sych tool.

The air filter is brand new one piece and the snorkel is not
restricted or bent.

I've got it running now but real rough---with sync tool in.

Thanks
dodjh

[dodjh]

T.C./'Tod,

The bar that the three sych. screws are on will not go to the
bottom of its travel. You can push on the tang with a screwdriver
and the rpm's drop but take the downward pressure off and
the rpm's increase.

I screwed the air/mixture screws in to a gentle seat and backed
off 1 1/2 turns. I'm trying not to have to remove the carburators again. The YICS tool I made I don't like, so I will try to find a
mercury type (unless you know of a better way.)

By the way I'm in MS. and been working on the bike since last May. I know you are familiar with all the time it takes to get parts
etc.

I appreciate any advice you would offer me---I'm so close and
yet so far away to actually driving it on the road.

dodjh

[TopCatGr58]

Hey Dodjh,

First, a little more confusion seems to be happening!? The YICS tool is made out of metal and rubber, it's to BLOCK the shared passages between the carbs in the head, so that you can get more accurate vacuum readings.

See This Tech Tip for the YICS Tool for clarification.

The vacuum gauge/synching tool is for getting the vacuum levels even between the carbs by adjusting those 3 screws between the carbs. You've got the Pilot screws done initially correctly.

I hate to ask, but take the throttle cable back off of the lever, and then see if the butterflies and throttle lever will bottom out? You may have the throttle cable set too tight, not enough slack at the handlebar??
T.C.

[dodjh]

carburator

T.C.

The YICS toool I have is the one on this web site made of 1/4"
copper and 3/8 O.D. rubber hose.

I did remove the throttle cable and noticed the adjustment
at the 90 degree housing under the handle bars is broken.
On the idle, I just pushed the bar down to the tang and adjusted
the idle screw up to where its travel down ward ended.
(that done with the throttle cable disconnected.)

The sync tool is the one shown on the web site made out of
PVC and aquarium valve. I don't understand how its used
to sync the carbs. If #1 is 7 psi and then you open up to #2
you turn the same screw used for #1 sync. So how does that work?

dodjh

[HobbyMan]

Ok here it goes. The yics is a passage way between the intakes for all the cylinders. You must plug it up to seperate the maifolds. Second, you want all the vacuum readings in each manifold to be the same. It order to be accurate, you measure the vaccume on 1 then 2(the left side). You must set the screw between those carbs so that the vaccume is the same for both 1 and 2. THen you do the same for 3 and 4. After you have the two cyls on each side, you must equalize the left and right side by adjusting the screw in the middle. After all is said and done, you remove the yics tool.

[TopCatGr58]

Dodjh,

You said you bench synched the carbs. Would the butterflies close all the way? If you have one of the other butterflies set less open than #3, then #3 won't close all the way, the tang won't bottom out, cause one of the other carbs butterfly is already closed preventing the connecting shaft from rotating farther to allow #3 to close so that the idle tang can bottom out!

When vacuum synching the carbs with that homemade gauge, you've got the aquarium valve, so you can connect ALL 4 carb boot vacuum ports at the same time, and then just open the valve for each one separately that goes to the vacuum gauge.

You measure the vacuum for #3, then check for #4, and then do a small adjustment raising or lowering vacuum level, then recheck #3 and then #4, cause like you said, when you adjust one, the other will change, as well as the idle speed may also change, and you'll have to adjust it as well back down. Once you get #3 and 4 same, then you repeat process for #1 and #2. Then you repeat for #2 and #3. When #2 and 3 are same, then ALL 4 are now synched!

This is why folks like the 4 gauge or mercury sticks, less fiddling with the aquarium valves to get all set same!
T.C.

[dodjh]

carburator

H.M.

I understand the process but how can I sync 1 and 2 by using the same screw. What psi do you strive for on 1 and duplicate on 2 because your uslng the same screw.

I'm using a vacuum guage and a 4 gange valve and can only read one at a time. I may have answered my on question. You open #1 and see what its reading and then close # 1 and open
#2 and see what it is and strive for the level between both carbs.

Is that right?

dodjh

[HobbyMan]

you set one carb relative to the adjacent one. Each carb does not have it's own adjustment.

[Ken Talbot]

That is correct. You are not striving for a particular vacuum reading for each carb. Rather, you want the reading for #1 and #2 to be the same, whatever that amount is. You then want #3 and #4 to be the same. Finally, you want the left side to be the same as the right side. Then your carbs are in sync.