1980 Carbs

[natemoen]

For those lurkers that may be reading this, there's another way to 'measure' your float height without calipers.
Make yourself a go/no-go gage. I take a small piece of cardboard (or any other sutiable material) and using my ruler, measure off the required amount and put a ink/marker line there.
(Note: the required height is different for the type of float, sorry don't have those exact numbers in front of me)
Then you can set the cardboard "stick" next to the float and bend the float tab up or down as needed to get the bottom of the float to match up to the mark on the measuring stick.
Remember to NOT push the float down, just let it rest on the needle.
If one side of the float pair is higher than the other, you may need to 'twist' the float to get both floats to match the same height.

This may get you close but I would say it is not exacting enough.

[GLoweVA]

This may get you close but I would say it is not exacting enough.

I would think that as long as the ruler I use is acurate enough and the line I use to mark the gage with isn't too fat, then it should get me within the tolerance (+-0.5mm) of the required measurement.

I kind of agree with you about removing the float to make the adjustment, but with the history of the float pins and posts sticking, I find it's easier to make the adjustment with the float on the pin, but just making sure that I don't stress anything else in the process.

[natemoen]

Once you get the pins out the first time as long as you clean it up and shave of the pins so they are loose, they will never stick again.

[Jay60465]

Thread Jacking 1980 special Carb Help

yeah my pins felt like they were welded in (lol). But when I put them back in i did not push them completely in like the PO did. I think this is my last float question. Do I take the the measurement from the floats on the resting position with the carbs upside down. thank you all

[bikerphil]

Yes, with the carbs upside down on the bench and float bowl gasket removed, measure from the gasket surface to the highest part of the float. Do not press down on the float, measurement should be taken in it's natural resting position Brass floats, the reading should be 1" (25.7mm). Measure each float bulb (8). Adjust by bending the tang at the float valve, if the other side bulb needs adjusting, carefully bend it in the right direction.

[MPittma100]

Jetting

I have had good luck with changing the main and pilot jets from the 78E carbs into the 79SF carbs. Throttle response and warm up is much better. Overall driveability is improved. Getting 3 MPG less (38-35), but worth the change for the added performance.

MP

[donebysunday]

Auto punch

Use a pencil style automatic punch for locating your drill mark to remove the pins, much better than breaking off the float tower. DAMHIK

[Jay60465]

carb thread jacking

okay I adjusted all the floats to 25.7mm with a digital caliper from the base w/o the gasket to the top of the floats. Yet the carbs continue to overflow. I was wondering if the float needle valves have to be seated a certain way. Or is there a chance that I actually got defective needles from the rebuild kit? I am using a old tank and using a "t" fitting to feed both carbs, can this cause them to overflow.

[bikerphil]

I am using a old tank and using a "t" fitting to feed both carbs, can this cause them to overflow.

Yes, it can. Another fella on here had the same issue, his aux. tank was too high above the carbs creating too much gravity pressure. Try your aux. tank just slightly above the carbs, not higher than 1'. Also make sure you are feeding fuel to the lower T's only, the upper T's are for vent and are not a fuel inlet.

[Jay60465]

carb thread jacking

Is there a way to test the float needles. I am thinking if I increase the float height it will cause the float needle to close sooner, thus causing a for sure closure. Is this theory correct? I am not to concerned about driving the bike anytime soon, so I have time to test theories and ideas. Thank you bikerphil for your insight on the aux tank.

[natemoen]

Don't change the floats in an attempt to fix a flooding problem. The float setting is not the issue. Either the floats are hanging up on the bowl gasket or something is holding the float valve open.

You didn't answer Phil's question either. Are the fuel lines connected to the lower T's on the carbs? Are the upper T's open to the atmosphere?

[Jay60465]

thread jacking

I have the fuel lines connected to the lower t's closest to the bowls then I have the upper t's vented to the atmosphere I never thought to check the gasket overhang ...great call

[dpotter58]

Is there a way to test the float needles.

With the carbs off and empty, hook a tee on the fuel inlets and blow into it. air should pass through. Flip them over to simulate the floats being up and you shouldn't be able to blow air in them

[Jay60465]

thread jacking

I like the air test I am guessing you cant put too much PSI cause I think gravity fed is like 3psi or something

[GLoweVA]

I got to ask, could it be possible that those 2 floats are bad?
In other words, they hava a small leak and thus stop floating cause they fill up with fuel.
You'd notice this the first time you pull the bowls off after having them filled and see/feel the fuel inside the floats themselves.
Just a thought so that we're covering every contingency.

Question for you 78/79 owners, do the older carbs with the screw in float needle seats have an oring like the 80/81 press in float needle seats?
The 80/81 have had a few leak past that o-ring and cause overflowing.