Ok Im as sick of this as Im sure most are but still need to figure it out. For some reason when adjusting the Fuel level in my M1Concentric with the new "stay up float" to the .210 +_ .040 just as a friends did the top of my float is sticking up about 1/4" above the top of the float bowl whitch means that when putting the top of the carb back on of coarse it will be hitting the float... My needle seat is flush or just above the bowl so what gives??? My friend cut his float down but I can't help but think Im doing something wrong here. This is being done in a vice, in a machine shop & using a pro depth Gage etc so I trust the #'s... Totaly cunfused, what is wrong? Does the needle seat need to come up? But that would be extream, allmost a 1/4"... Anyone have a idea???
Confused readings w/ Stay Up Float.
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DogT
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About half way down this page. https://www.ntnoa.org/pdf/Bushmans Carb Tuning Secrets.pdf
I found the Burlin settings not to work with mine, I could not even get them to tickle. I had to go back to my original settings, like about .08 below the top of the bowl. Make sure you're holding the tang down when measuring, not the needle. You can also adjust them on a flat plate with fuel or alcohol, so you can actually see what's going on and even if the needle seats leak. Let me know if you need a pic of my setup, it's real easy.
Dave
69S
I found the Burlin settings not to work with mine, I could not even get them to tickle. I had to go back to my original settings, like about .08 below the top of the bowl. Make sure you're holding the tang down when measuring, not the needle. You can also adjust them on a flat plate with fuel or alcohol, so you can actually see what's going on and even if the needle seats leak. Let me know if you need a pic of my setup, it's real easy.
Dave
69S
Just fitted the new stay ups as I was having a stupid fuel issue. I figured the easier adjustability had to be good. Measured depth of 0.57" +/- a gnat's wotsit seat to bowl face gave me a float position 0.04" below the bowl edge (opposite hinge pressing on tang and holding pin in place. Sorry didn't measure the fuel level a la Dog T but why not start there. FWIW I got varying results each time I replaced the float and found the pivot pin bent so it depended where it ended up each time.
DogT
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Personally I think the numbers are bogus. When you push down on the tang, seating the needle in the seat, you want the front of the float (opposite the tang) to be about .04" below the top of the bowl, itself. You can bolt the bowl to a flat plate, a single 10/32 will hold it and the gasket on, with the bar, and you can put fuel or alcohol in it and see exactly what it's doing. The float should hit nothing when it's working and if you don't get tickle, it's too low, that's what I got with the .08, too low and no tickle, so I set mine at .04 and it seems fine, that's what it was when I got the bike. YMMV
Dave
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Dave
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DogT
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gtsun said:
If by 'Float height' you mean the measurement from the top of the bowl to the top of the float while holding down the tab, yes. That's what I'm saying, but you will want to check that things don't leak and it works for you. Best test is if you get good idle at 1 1/2 turn out with the idle pilot, then float is right. My bike and carbs are real old, but I did put anodized slides and the new floats and needle valves in them.
Did you look at the Bushman's page? The picture is quite apparent, but I used .04".
I couldn't get anything to work with the Burlin numbers. Like I said with .08 I couldn't even get it to start or tickle, moved it to .04 and it's been working fine. I really didn't measure the actual height of the fuel in the bowl, I just go by the float to bowl top measurement. YMMV.
The setup also checks your needle seat if you let it sit there with pressure on the line. If it leaks, you'll see the fuel height keep going up and you will never have a consistent fuel level and it will eventually leak out the gasket. Don't need no stinkin' fires. One of mine leaked, they're fixable. I used an old turkey baster at the top of that fuel line to hold the fuel.
Dave
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DogT said:
Thanks very much for the photo and text, that is a clever setup and an excellent method to see how the floats and valve are really working.....FWIW the PO did not set the float and valve up right on my bike and I did indeed have a fire which I very fortunately was able to extinguish with my gloves.
DogT
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I was really surprised how much one of my needle valves leaked. When the bike is running it's hard to tell, but sitting at an idle, it would flood and fuel would come out of the gasket. As I see it, the bowl/body gasket is there to keep air from getting it, but it certainly doesn't keep fuel from getting out. Just watch the gasket when you tickle it. If you don't check this, you really don't know if your needle valves are leaking unless you see fuel dripping off the carbs while you're sitting at a light. Not cool.
The other thing that needs checking is your petcocks. They too can leak like crazy and you may or may not know. I lost a whole tank of avgas overnight from a leaky petcock. Luckily it evaporated from the float bowl and not into the engine. Avgas really evaporates fast. Put your tank on a bench with the petcocks turned off and put a paper towel under them and see what happens in a few hours.
Don't need no stinkin' fires. We've seen enough lately.
Be careful out there, there's enough that can go wrong without asking for it.
Dave
The other thing that needs checking is your petcocks. They too can leak like crazy and you may or may not know. I lost a whole tank of avgas overnight from a leaky petcock. Luckily it evaporated from the float bowl and not into the engine. Avgas really evaporates fast. Put your tank on a bench with the petcocks turned off and put a paper towel under them and see what happens in a few hours.
Don't need no stinkin' fires. We've seen enough lately.
Be careful out there, there's enough that can go wrong without asking for it.
Dave
One thing I noticed was my pin that the float pivots on was worn & it's a real sloppy fit. It also is slightly higher than the groove. The gasket probobly takes that up but mine was trashed so I bought a # 37 drill blank & cut it to fit & took down the ends a bit so it doesn't interfear with the gasket sealing. I'm using one of the aluminum Viton tip float needles & in my tests with a gas line hooked up it seals fine, no leaks. I'm doing one for my BSA 441 too, wish I could find a forum for that bike as easy to navigate etc as this one... Anyway, fingers crossed all will be fine. Thanks.
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