XJ1100 carb float adjustment concern

[KA1J]

I've balanced my carbs on a jig so that they are dead level in all directions

Here's how I leveled the carbs:

Carbs on the jig. Note the bulls eye level with washer below on top of #2 carb


How I adjust so the bulls eye level is centered (the rear two feet are also bolts and are adjustable)


How the bulls eye level looks before leveling


What the bullseye looks like when the carbs are made level.


With the carbs squarely fixed, I'm finding some of the fuel levels were as much as 7-8 mm too high in the sight tube. It says in the manual to slightly bend the tab to adjust the float level. All of the tabs were almost parallel with the metal connected to the floats. It was hard to get anything in there to bend the tab but finally I did, The metal is pretty thick and does not want to bend. Finally after bending the heck out of the tabs I get the level to be 3mm below the carb mixing chamber edge as shown in the manual.

Problem is the manual says to bend "slightly" the tab & I've had to really bend them way down, it's almost like the valve should have been 1mm or so longer instead. I measured the old needles and they are the same dimensions as the new replacements, just the rubber tip is now new.

This is the float from carb 1 and I've bent all the tabs this far upward from flat and while carbs 2,3 & 4 now have the fuel level at the proper place in the sight tube, this tab for #1 needs to be yet more bent to drop the level another 3mm. I'm afraid more may break it.




It doesn't seem right that these floats would have to be adjusted so much to get the fuel to be at the proper sight level marks. Am I doing the right thing in placing the carbs at true square to ground and making the adjustments from this position? Isn't this an excessive "slightly bending" of the tab?

I can't find anywhere in the manual where it says to adjust the floats dry, much less at 23mm as posts relating to the later XS say to do. I'm holding off on doing further work on these till I get a consensus on what's going on.

Thoughts?

[mack]

tangs

Well, take another picture showing the position of both tangs on that carb body. I don't know what floats you have but the boyancy of the china ones are all over the place. As much as 3mm between floats that I have purchased.

[KA1J]

Well, take another picture showing the position of both tangs on that carb body. I don't know what floats you have but the boyancy of the china ones are all over the place. As much as 3mm between floats that I have purchased.

Here you go. Don't know the history of these floats but they are what came on the bike. The bike has 19K on it so the floats are likely original.

Float hinge/tab from above

[psycoreefer]

Just wondering, how did you attach your carbs to your leveling jig?

[CatatonicBug]

This measurement is supposed to be taken with the carbs in the bike, with the engine running. That's why they have the side-facing drain tubes. It's designed to get a real-world measurement, based on real fuel flow through the carbs. Not sure that doing this test in a static environment will get you accurate results.

[KA1J]

Just wondering, how did you attach your carbs to your leveling jig?

Pipes that fit the ID of the carb outlet. They're about 2" long & JB Welded to the plywood backboard.

[KA1J]

This measurement is supposed to be taken with the carbs in the bike, with the engine running. That's why they have the side-facing drain tubes. It's designed to get a real-world measurement, based on real fuel flow through the carbs. Not sure that doing this test in a static environment will get you accurate results.

After all the true grief to get these carbs out & in of the XJ11, I don't in any way want to do & re-do that to adjust the float bowl settings till I get it right. If it were simply to get things adjusted by easy removal of the carbs I could do that but this bike was not designed to remove the carbs without a battle. Then another one to get them back on. Ugh...

[psycoreefer]

I don't see why there would be any difference bike running or not - the level they float at is the level they float at. However the "level" may be quite different on the bike vs off the bike.

I'd do this...
Stick the carbs on the bike with as little work as possible (I don't have an XJ but on an xs if you pull the air cleaner its simple to pop the carbs on and off)
Then make marks or take measurements of how the carbs sit (front to back degrees off level)
Then stick them back in your rack and adjust to match the front/back angle they had on the bike and adjust the floats.

[motoman]

A good cheap way of checking wet levels. Interesting though that a 23mm float setting on the later carbs will be real close to the wet level setting of 3mm. With a level across the tops of carbs while mounted and small wedge used under centerstand leg to level carb assembly works very well also. No getting around removing carb assembly to adjust, install, check, remove as necessary till ALL carb fuel levels are IDENTICAL! Bit of a PITA, but can remove carb bank using the stock airbox in 10min. or less and re-install running in less than 15min. As Ken T. stated on here a few years ago, the float levels being ALL identical is a very critical factor for all four carbs to perform the same at any given rpm range, aside from making the tuning process easier. Also that 3mm +-1mm does NOT mean a 1mm variance between the four fuel levels either! Yea, removing and installing the carb bank on the XJ is a bugger!

[bikerphil]

I've set the float levels on XJ11 carbs before using the conventional measuring of 23MM above the bowl gasket surface with the carbs upside down. With good results I might add. Might want to see if your settings are close to the 23MM measurement.

[XJ Rob]

My .02

I would use the jig you made to get the correct fuel level. Put the carbs back on and sync them. I did mine without the extreme leveling jig you have and I have no problems. I used the washer on the bowl screw as a fuel level point. Everyone has "their" own way that works for them. That is what I did for my XJ. My bike runs great.

[lancelot455]

After all the true grief to get these carbs out & in of the XJ11, I don't in any way want to do & re-do that to adjust the float bowl settings till I get it right. If it were simply to get things adjusted by easy removal of the carbs I could do that but this bike was not designed to remove the carbs without a battle. Then another one to get them back on. Ugh...

i can pull the carbs off my XJ in about 5 minutes

[DGXSER]

The true directions for checking the fuel level on the bike is to actually level the carbs on the bike. So the on bike level should match the off the bike level with this setup.

They also recommend this method for the SH model, it has the same side outlet drains. Like Phil, I have never used that method, I simply set the floats at 23 mm, make sure my the float valves seal, and then load them in the bike. Synch, tune, synch, and ride. Like Phil, never had an issue with them running god.

[Yahman]

i can pull the carbs off my XJ in about 5 minutes

Show off!!!









Larry

[KA1J]

Thanks for the suggestions thus far.

When I read the manual on fuel level measurement (page 4-5) it says: "Adjust the motorcycle position by placing a suitable stand or a garage jack under the engine so that the carburetor is positioned vertically".

The way I interpret that is that the carbs are supposed to be checked when level as they were on the jig I made when I had the carbs resting square at 90 degrees. Perhaps I am misunderstanding the words and that's not what they meant. Assuming they didn't mean the carbs should be 90 degrees to level I balanced the bike and then measured the resting angle the carbs sit in the manifolds using a flexometer to the back of the carbs & they're tipped forward at 5 degrees. I'll set the jig with a 5 degree forward tilt & check how the sight level relates to what it was before.

It also says "Start the engine and stop it after a few minutes of run. This procedure is necessary to obtain the correct fuel level". That sounds like the idea is to run fuel through the float bowl. Since the only thing the sight tube measures is gas height in the float bowl, perhaps the reason to run fuel through it is to purge air from the bowl? What makes sense to me is if I run fuel into the carb & drain it through the float bowl nozzle for a few minutes, it will do the same thing as running the engine & run gas.

I have a one gallon lawn mower gas tank I use while syncing the carbs and I'll run fuel through the carb & let it run for a while. I use a filter inline from the mower tank so I can keep reusing the fuel & if I run a half gallon of gas through the bowl, that ought to (I think) be the same as running fuel through the carbs "for A few minutes of run." Out of curiosity I'll check it first when filling the bowl & then again after running the fuel through it.

It seems like the main thing I need to know to adjust these floats properly is exactly what did they mean by adjusting the bike so the carbs are positioned vertically? If it means square as I thought, then the only thing I didn't do was to run fuel through the carbs for a few minutes.

More thoughts on this?

Thanks