1980 VS 81/82 float adjustment

[KA1J]

With the 78-79 carbs the round float bowl levels were adjusted to 25.7" from the bottom of the float to the float bowl gasket surface.

Come 1980 the adjustment went to 23mm +/- .5mm

In 81 & the 82, XJ11 float measurements changed to the on bike level method and sight tube.

Any idea why the change to the sight tube?

Is measuring 23mm +/- .5mm instead of using the on bike method a bad idea for these later carbs?

[DGXSER]

I have never used that on bike method, and I have set up a number of 81 carbs. I always measure the 23 +/- .5 mm.

HTH

[KA1J]

Thanks for the thoughts.

I tried the tube method but the tabs were being bent too much to seem right. On the XJ650J their tabs have nearly zip for bend & are just right when measured. With the sight tube on the BS34 I had them with maybe a 10 degree bend in the tab & that's seemingly just too much.

Will do that 23mm today.

[KA1J]

XJ11/latest XS11 carbs; I'm wondering where to measure the 23mm. I'm looking at where the float and the way I'd bent the tabs before, the float angle from the hinge is pretty steep.

I took a plastic straw, measured the distance between the flat part of the float to the end of the float bowl. I doubled that length and cut a plastic straw at that point. I wetted the middle of the straw and laid that on the flat part of the float so the middle of the straw would balance easily and stay flatly in place so I could measure from the bottom of the straw along the float bowl and have an accurate point to measure to.

At the base of the float by the tab it is 22.48mm from the metal that the gasket rests on. Following the bottom of the straw to the far end of the float bowl it's 28.61 to the end. That's a 4.13mm difference from one end of the float to the far end of the float bowl.

Where along that line do I measure the 23mm +/- .5mm?

[MrOzz]

You measure the 23mm at the flat part of the float. I measure where the metal meets the plastic float.

Hope that helps you.

[DGXSER]

Actually, you want to measure at the highest part of the float, which is typically the flatter area just before it starts to round over. The part where the metal attaches is a bit of a step down from the main float area.

[MrOzz]

Actually, you want to measure at the highest part of the float, which is typically the flatter area just before it starts to round over. The part where the metal attaches is a bit of a step down from the main float area.

Sorry,

Thats the area I was talking about. I should of been more specific.

[KA1J]

What I did was to measure 23mm using a digital vernier caliper and used the tang, the thin strip of sliding part that extended out the end of the slide to measure with. I used the end of the slide as the marker (as I did measuring middle & rear oil fluids).

I made it a really exact 23mm so that when I pushed straight down on the distal part of the flat part of the float, I saw no movement on the slide (watching the reflection on the metal tab on the other half of the float for movement). When I rocked the end of the caliper ever so slightly I would see a change in the reflection & called that 23mm.

I also did this with both sides of the float as I discovered they were not equal, one was always higher than the other. So I'd hold the float that deflected the least up off of the valve and then bend the other float toward. Any method would do but I kept correcting the two sides till they were even & then adjusted the tab on the float to go up or down.

End result was 23mm on both floats.

Thanks for the tips, I think these ought to be just fine now.

[scott0757]

I also had the different sides of the float at different heights and had to spend time leveling them off and in a manner. My 80 Special has the plastic body floats and the manual says to measure .906" +/- .020.
My my question is do you measure the float height when it's just resting on its own or are you supposed to compress the small spring in the float needle to assure it is really seated? It makes a difference for sure.
After my last rebuild it seems to be running OK, but the gas mileage has really dropped off by 40% so something is not right....the float height is the only thing I have left to check out...

[DGXSER]

Float height is measured with the gasket removed, and the floats at rest. So no, do not push the floats down to compress the spring.

[skids]

Float height is measured with the gasket removed, and the floats at rest. So no, do not push the floats down to compress the spring.

There is a raised line to help seal the gasket. I measure from the flat part of the mating surface rather than that raised line.

[TADracer]

If you have the capability to measure the bowl level with tubing instead of the float height, do that. It is a bit of a PIA and is easier to do on a bench if you have the carbs out instead of in the bike. Plus, if you must make an adjustment you will need to remove the carb rack anyway. Measuring the fuel level in the bowl willl give more accurate results and might even stop some of that nagging dripping that many seem to have.

You would be surprised at the difference things like minor variations in thickness of the gasket under the seat or differences in compression of that little spring inside of the needle or even small differences in the weight of the floats themselves can have on fuel level in the bowl.

All I can say is this from experience, when I set up my new Keihin carbs I checked the floats heights and they were dead on factory. Checked bowl level with some tubing on a level stand I made and the fuel levels were all different. Not by much but then a single mm can make a difference in performance.

[DanSG]

I have a question as to what my correct float hights should be: 23 or 25.7 mm?
My bike was manufactured in 7-79 and has pilot air jets like a 79...however, the book with the bike says 1980 XS 1100SG and the title says 1980. Frustrating.

[bikerphil]

If it has brass floats it is probably the 25.7mm setting, plastic floats the 23mm setting.

[motoman]

On the later carbs that measurement is to the flat portion where the metal tab attaches. The wet fuel check is done ON the bike with bike running. What I found was the 23+-.5mm static setting will get the running wet level on all four to within a thin pencil line of each other and will put the RUNNING fuel level at the 3+-.5mm correct RUNNING fuel levels. I took the .5 for the 5000ft.elev. and most of what I ride with this bike is w-a-y above that.