Topic: CB550 Carb Float Height Question

[jude0007]

I got a 76 CB550 for next to nothing.  The carbs were in decent shape but soaked them, cleaned them, etc.  Not perfect but getting better.  I ran fuel through them and they leaked as fast as I could get fuel into them through the overflow nipples, indicating that the float heights are incorrect or the float needles are bad.  The PO said needles, gaskets, etc were new (he was trying to restore the bike but failed).

Manual shows the float heights should be set to 22 mils.  When I checked them, they were way off, set much higher.  I tried to adjust them to 22 and it seemed really counter intuitive.  If they were seating, they should be adjusted lower. I put the carbs on their side to the point that the tabs didn't press the needle so I believe I'm testing them correct.

As the picture shows, it's not quite set to 22 because when I push the floats all the way down, bottomed out, they are about 22 mils.  That doesn't make any sense.  I don't think they are on upside down.

What the hell am I missing? 

[reddyvv]

You need to put the ruler on the edge of the carb where the float bowl sits. Looks like you have the ruler down inside the carb, can't tell for sure?

[jude0007]

You need to put the ruler on the edge of the carb where the float bowl sits. Looks like you have the ruler down inside the carb.

I have it sitting on the float bowl surface like it should be and like you mention.  Pictures might be deceiving.

[reddyvv]

Why can't you bend the tabs to get the height right? We need a couple more pics.

[jude0007]

I could bend them to get the height correct but the actual floats would be bottomed out at 22 mils.  And then there would be no way the floats would compress the float needle at all.

I've gone through a few sets of carbs before on other bikes no problem.  The PO has given me a few good surprises with parts not original to the bike.  I think these carbs are correct but I just don't understand what's wrong.

What pictures would help?  Thanks for the help!

[reddyvv]

Post up a couple of pics of the float needle and seat, and the float itself so we can tell if it's original. Are those 022A carbs? Should be stamped on the body.

[jude0007]

Yes they are. The indentations on the floats point down when on the bench (technically up when installed)

[reddyvv]

Can you post a side profile picture of the float? It looks like the plastic floats are bent in relation to the brass crosspiece. The casting marks on the floats should line up in the same horizontal plane as the brass holder - if that makes sense.

[reddyvv]

Like this

[goldarrow]

Possible floats are upside down???

[TwoTired]

Um. The spec is 22mm. Not 22mils.

[jude0007]

Like this

That's definitely not how mine look.  Please see pic.  Think you're onto something here.

[jude0007]

Um. The spec is 22mm. Not 22mils.

Right, that's what I meant. 

[jude0007]

bump

[goldarrow]

Put up pics how you measure float height

[jude0007]

I found this picture on my phone and added a line as to how I measure the float height.  I measure 22 mm from that float bowl surface to top of float.  I will confirm that the floats are not bent as the previous post mentions. 

[goldarrow]

The way you hold the carbs while doing the measurement is very crucial.  Did you tilt the carbs while measuring?

[jude0007]

Yes I did, the picture above with the red line is not while I was actually measuring/tilting.  It was difficult to measure and take a pic with the ruler all at the same time....

I put the carbs at an angle to the point where the tab just barely touches the float needle but doesn't compress it. 

[goldarrow]

Well, seems like you're on the right track.  Another thing I could think of, check and look on the float tang real good, sometimes float stuck because of little pit on the tang (where the float needle valve touches the float tang.  Polish it float tang flat shiny. 

edited couple of words above

[lucky]

Yes I did, the picture above with the red line is not while I was actually measuring/tilting.  It was difficult to measure and take a pic with the ruler all at the same time....

I put the carbs at an angle to the point where the tab just barely touches the float needle but doesn't compress it.

The plastic floats are so light that they do not depress the float needle when upside down.
If you do not believe that then do it yourself and you will know.

With the older brass floats that were much heavier, it was true that that you could not measure them when upside down.

If you had bought a WORKSHOP MANUAL you would not have had all of these problems, and bent your floats all up.

[jude0007]

This is normally too easy.  I fear I have some incorrect part that the previous owner swapped out.  I'll check a few things, post some more pics and then it might be onto buying new float needles, etc.  I don't really want to replace the floats because I think they're correct (and they're expensive)

[TwoTired]

The plastic floats are so light that they do not depress the float needle when upside down.
If you do not believe that then do it yourself and you will know.

I have.  And they do depress the original spring pins, leading to incorrect height setting.
Aftermarket needles sometimes have stiffer springs, so that they can support the float weight.

Measure the float height with the float's pivot pin vertical, to remove any variability due to float weight or spring strength.

[jude0007]

Yes I did, the picture above with the red line is not while I was actually measuring/tilting.  It was difficult to measure and take a pic with the ruler all at the same time....

I put the carbs at an angle to the point where the tab just barely touches the float needle but doesn't compress it.

The plastic floats are so light that they do not depress the float needle when upside down.
If you do not believe that then do it yourself and you will know.

With the older brass floats that were much heavier, it was true that that you could not measure them when upside
down.

If you had bought a WORKSHOP MANUAL you would not have had all of these problems, and bent your floats all up.

I do have a workshop manual.  See the picture below, the floats look exactly like mine currently and not like the gentleman above posted.

[jude0007]

I was thinking, is it possible I hooked fuel lines up to the wrong two connections?  Since I got the bike in pieces and can't find a reference in the manual or online, I assumed the two larger connections were fuel intake and the two smaller ones were vacuum breathers? 

This would be utterly dumb but an easy fix.

[goldarrow]

i looked back post reply #16 above, i have a mixed feeling that you have your floats flipped.   please double check and verify.

this picture is from my cb750 carbs, but same idea as to how you would adjust the float heights.