Carbs float height

Carbs float height

Postby sneck » Wed Dec 28, 2011 6:17 pm

I have rebuilt the carbs on my Z but I am getting number 3 and 5 carbs slightly overflowing I have tried to measure the float heights but what do you use for checking the float heights besides the factory tool,( something that the DIY mechanic may have to hand in their garage ) other than that I am assuming it may be a float valve not seating correctly .I am considering if its worth moving the float valve to another carb (on the bench with fuel feed) and see if the problem moves or stays with that carb .

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Re: Carbs float height

Postby ajs350 » Wed Dec 28, 2011 6:44 pm

Sneck
The Honda tool is the right way but you can check the float heights using some clear tube attached to the drain tubes. Be sure to set your carbs on the bench at an angle that represents how they sit when mounted to the engine. I used 2 pieces of 2 by 4. The fuel level should be at the top of the back plate screw you see in the picture.
If your float valves have been sat for a while the plungers at the top may be stuck. Soak them in carb cleaner and push the little plungers in and out to free up any crud.
Ross
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Re: Carbs float height

Postby sneck » Wed Dec 28, 2011 7:13 pm

ajs350 wrote:Sneck
but you can check the float heights using some clear tube attached to the drain tubes.
Ross
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You've confused me with what you call drain tubes Ross , have you another pic of other end of the tube what it is attached to ?

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Re: Carbs float height

Postby ajs350 » Wed Dec 28, 2011 7:55 pm

The drain tubes are what stick out of the bottom of the float bowl. You undo the screws and petrol drains out of them on to the floor!
Here's a better picture but the fuel level is too low only coming to the bottom of the carb frame screw.
Sneck if you want to do this right you really need to buy the tool or borrow one from a local club member. I would lend you mine but UK postage from the US to the UK and back would be the price of the tool. :D
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Re: Carbs float height

Postby sneck » Wed Dec 28, 2011 8:21 pm

I am with you now Ross,

Is there a special fitment or does the pipe just go onto the drain tube, just thinking is it something that can be made

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Re: Carbs float height

Postby ajs350 » Wed Dec 28, 2011 8:34 pm

Sneck
The tube just goes straight onto the drain tube. Take your existing black drain tube to an auto parts store and ask for a clear equivalent
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Re: Carbs float height

Postby sneck » Thu Dec 29, 2011 4:34 am

Thanks for your help Ross

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Re: Carbs float height

Postby Kool_Biker » Thu Dec 29, 2011 9:15 am

Hi Sneck

You might want to check this thread also ... viewtopic.php?f=20&t=7436

Best, Aris
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Re: Carbs float height

Postby sneck » Thu Dec 29, 2011 5:28 pm

Thanks Aris , read through that post earlier will also check float valves

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Re: Carbs float height

Postby oldschoolcarbs » Fri Dec 30, 2011 3:15 pm

Sneck, I doubt very much that you're overflowing due to incorrect float height but let's explode a myth in that regard anyway.

You don't need a float tool.

Remove the bowls and rest the carbs on the bench as shown. The floats are now hanging in such a way that they're barely kissing the needles without depressing the plunger springs.

Use a very thin screwdriver to bend the tang up or down to achieve the perfect height, which is when the casting marks on the floats are exactly parallel with the gasket surface. Honda designed them this way for a reason. It's impossible to imagine a factory full of workers who are each meticulously measuring each and every float when all it takes is a good eye and the ability to use a screwdriver.

This float is as it arrived (and after undergoing the full series of cleaning processes and the carbs being assembled.) Setting heights is our final step before buttoning the bowls up. A previous rebuilder installed new float seats and didn't account for the differences in milling depth between the various manufacturers. These are Keyster seats and needles, which is to say that they're high quality parts but he missed this detail so it didn't run properly and had to be redone. (He hadn't prettied them up very well either.)

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This is the same float about thirty seconds later (most of that time was in picking up the camera), which I've set to a too rich position on purpose.

4951

This float is right on the money, again perhaps thirty seconds or so later.

4952

Just make sure that you use line of sight exactly at the plane formed by the gasket surface in order to ensure that the float is perfectly aligned and you're set. Plus, give them a few minutes to settle before replacing the bowls in case the metal tang rebounds a tad, which is fairly common if you find one that's way out.

Hope this helps!
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Re: Carbs float height

Postby sneck » Fri Dec 30, 2011 6:19 pm

Hi Guys

first of all I have just read the previous post now (thanks oldshoolcarbs) which makes common sense, but I am thinking I may have a bigger problem here!

I have slackened off the drain screws and put plastic pipes on the drain tubes and the level is varied on some off the carbs ,my question is where the fuel level is too high which way does the float want bending bearing in mind that when working on them they are upside down
one is flooding through the carb bore its that high so do I have a major problem or can it be fixed by adjusting the float
I really appreciate your help and time on helping me with this problem, thanks Guys

Image
this is the one which is way too high

Image
I assume these are about right

Image
and this is too high as well right!

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Re: Carbs float height

Postby oldschoolcarbs » Sat Dec 31, 2011 2:59 pm

Sneck, you're going to have to flush out the affected float seats and inspect all of the float needles so the first step is to drain the fuel and pull all of the bowls off.

If fuel level rises to overflowing you've got either 1) some debris caught under the tip of a needle, 2) a bad seat, 3) a bad needle, or 4) they aren't engaging the teensy bail wire correctly. To be safe, pull them all and flush some fresh, filtered gas through them. I use a pump to accomplish this because it speeds up the process and eliminates variables but gravity feed will work in a pinch.

Carefully inspect the tips of the needles for even the slightest ring of indentation, crud, or wear. Then install them all and check and adjust the floats using the photos in my last post.

Reattach the bowls and with the carbs resting upright on the bench (in one of your wife's cake pans) fill them with gas. If they hold overnight you should be good to go.

If they're still seeping you're going to have to address the seats and/or needles. You can determine which is which by swapping them around. Use a bright light to inspect the interiors of the float seats for burrs but understand that not every imperfection is large enough to be seen. Holding for hours will tell you if it's good or not.

Keep on slugging and eventually you'll be eating bugs again!
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Re: Carbs float height

Postby sneck » Sun Jan 08, 2012 6:49 pm

I have set all the float height/levels to 15.5mm using a vernier guage because I dont have factory tool and all the needle valves look okay and appear to be seating correctly.

My problem being I am certain that I dont have a leak but on attaching clear plastic tubes to the overflows to check the fuel levels they differ by quite a lot and the only way to get all the fuel levels the same seems to be to adjust the tang on the float but this takes it away from the 15.5mm measurement bearing in mind that they is probably a tolerance involved in the 15.5mm.

which is most important the 15.5mm float height or that all fuel levels are about equal or is there something wrong here?

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Re: Carbs float height

Postby bobber01 » Sun Jan 08, 2012 11:05 pm

With the floats all set the same, 15.5, and there still being some difference when using the plastic tubing indicates, to me anyway, that there's an issue with the floats themselves. Are they all the same in shape? Same dimensions? Possible some floats are cracked and have fuel leaking inside? If you had a gram scale may want to consider weighing them. Are all float valve dampers working properly, not possibly sticking?
I just finished, today, rebuilding a set and installing. I almost got caught with the first float of installing up-side down with the tang pointing done. But damn does she ever run sweet now! And haven't even sync'ed them yet.
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Re: Carbs float height

Postby Mike Nixon » Mon Jan 09, 2012 12:52 pm

Adjusting float height is *never* the correct way to stop an overflow condition. Check for cracked overflow standpipes, extremelely common.
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