floats on carburetors

[johnfrenchsr]

How do you adjust them.

[sermn8ter]

you are being ignored

But since I am pretty new and prone to ask a dumb question ever now and then myself, I'll help you out. Look in the Tech Tips section first to see if anything is there, and if not, then go to eBay and buy the service manual for 25 bucks. It has everything about everything. Then after having done all of that and you still have a question, somebody may talk to you. It isn't malicious though, so don't get upset about it. There is just no way anybody can tell you everything you need to know, and the manual is readily available.

[DiverRay]

The tech tips are a good start. The big thing is be GENTLE when trying to adjust the floats. You want to bend the tab that sits on the needle without putting any force on the needle.
The biggest thing is have all the carbs EXACTLY the same. Use the specs for your year, and if you are running a little rich, drip ip about 1mm. You will have the carbs off the bike, and upside down when you do this. you can pull the float bowels without takeing the carbs off the bar. Keep them together at all times, and you'll save yourself a LOT of work.
Ray

[Ken Talbot]

As DiverRay says, take the float bowls off and set the carbs upside down. You'll be looking at this:


You adjust the float level by carefully prying that little tab in the middle. Find a spot on the floats that you can measure to from the surface where the gasket would sit:


Get all four floats the same, starting at factory spec, then test for performance and plug colour. It will take a while, but when you find the correct combination of float level, jet size, exhaust type, and intake filtration, it will be sweet!

[xj11john]

Hey Ken

I adjusted my carbs the other day, measured my xj11 needles, and 3 were at about 23mm and one was lower, well Made them all the same, cause some of the carbs were overflowing into cylinders, #1 anyway, so anyway after I presynced-used some foil off a package-couldnt find a bread tie, so it was not as thick,
The rubber tipped needles were grooved pretty bad, so I tried to get some of the groove out, but i dont think i removed that much, but maybe enogh to make them leak, since today carb #1 was overflowing visable out of indy type filter!

also to back up, when i presynced the carbs, 3&4 seemed , could have been 1 & 2, butterflys were open more than the others, so I'm thinking I maybe taking these things off and on a bit to get it right, since now (and I bypassed the octopus) 3 &4 are lean and
1& 2 are rich-sooty, but I bypassed the octo because I repaired the diaphram with a epoxy that was gas resistant and I thought maybe I blocked part of the flow off, and thus the leaness could have happen, but I'm thinking now i just didnt pre sync with a think enough material,

what are your thoughts, ---its going to kill me to wait on needles and petcock rebuild kits -that also have a new diaphram for the octo form mikes,

desperate to ride---John

[Ken Talbot]

John, if you looked into the carbs after the pre-sync and two of them looked to be open a bit more than the others, that probaly just means you haven't quite got the pre-sync right. The whole point of the exercise is to get all 4 carbs to exactly the same opening. I think foil might be a bit too thin and delicate to work properly because it would tear if you got a butterfly a bit tight. The bread tie idea only came up because that is something that is usually pretty easy to find. All you need is a thin wire that is strong enough not to break if you get an adjustment a bit tight. The fact is, even with a bang-on bread tie pre-sync, your idle speed is going to be way too high because the butterflies are open so much. First thing you'll need to do is lower the idle back to around 1000 rpm.

[xj11john]

right

yeah i know what you mean, and it wasnt tin or aluminum foil it was part of a seal from a package that was rolled and sealed, kind of perforated, anyway it held up, and I got the butterflies all the same, and then lowered them to 1000 like you said the other day----what I was referring to was that before I Pre-synced they were a bit different, but once again I evened them out

I was just wondering if they were different for a reason, and the PO had them that way for a reason (since the bike ran good before I dived in--except for the gas-oil prob--but the idle was great)

any advice would be helpful thanks

[Pat Kelly]

I make sure to measure both floats in each carb bowl. Does no good to measure and set the right float and have the left one a little higher or lower.

[xj11john]

good thought

I never thought of that, I guess if the float was twisted one could be higher than the other side, since they are joined together on my xj

[CWilliamson]

Ken,

I noticed in your picture that the float needles have a metal wire holding them to the tab. I do not have these on any of my carbs (they are also all metal, no rubber at the tip). Is the wire to hold it in place normal?

Thanks,
Clark

[Ken Talbot]

That's a picture of later-model (80 or 81) carb. The mechanism on your '79 is similar, but just a bit different.

[CWilliamson]

Aaahhhh...That explains it. It matched my old '80 xs850 mechanism. Just wanted to verify as I picked up the petcock 4 hole rubber thingy at the dealership over the weekend and it was too large by about a quarter inch so I don't know what my petcocks came off of...thought it might be a conspiracy. ;-)

Thanks again,
Clark

[prometheus578]

the float needles have a metal wire holding them to the tab

I've run across carbs where the float needle has been stuck in the closed position. My estimation of the design is that by wiring the needle to the float, the "weight" of the float helps pull the needle down should it tend to stick.(in a gummy situation)
When doing small engines years ago... there was a right direction and a wrong direction to have the open end of the wire clip facing, but I'll be damned if I can remember how it goes now.

[Ken Talbot]

Clark - just for reference, here's a detail shot of an early-model float assembly like what's in your carbs. Note the screw-in float valve instead of press-in, and the lack of a wire that would pull the float pin back down when the float drops:

[CWilliamson]

yep

That looks like mine. Thanks for the folowup. My parts should arrive today so I can finish rebuilding the carbs. Have to wait on payday for the replacement petcocks so the bike will be a week or two from running.

Clark