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Old 06-18-2013, 11:46 PM   #31
supershaft
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Location: San Francisco Bay area
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You can get clear plastic bowls for our Dellorto's. I have never felt the need to use them but I have never had any issues setting the floats in them or Bing's.

We are all limited in what we can do. My advise is to stick to things that matter. Sniffing the exhaust while riding. Load changes EVERYTHING. How are you sure that isn't what you are tracking? Personally, I would set the level like I suggested and then put some bigger fish in my fryer!
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Old 06-21-2013, 10:09 PM   #32
rustygardhouse OP
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So I tried the white lightning jar as a float bowl idea...

I first tried it with the carb as is & holding my jar against the float bowl flange. The rake on the carb is such that the fuel spills out of the jar long before the float reacts.

So the brick went under the front wheel, the intake came off & the gasket was loosened to tilt the float bowl flange level.

The float was adjusted to the 'seam level with float bowl flange is off' idea. This is '23.5mm' on my float bowl reference marks.

Up went the jar against the float bowl flange, on went the fuel.

Which promptly overflowed the lip of the jar.

This could mean a couple of things:

1. the float is not as buoyant as a new float
2. I don't have the 'level is off' point correct
3. something else I haven't thought about

What this does confirm is something that I had suspected: for this model of carb the fuel level is very close to the top of the bowl when installed due to the floats, jet stock & other stuff that hangs down into the bowl, displacing fuel.

This makes measuring the fuel depth in the bowl very difficult; it is very easy to spill fuel from the bowl if the carb isn't dead level when the bowl is removed.

Which is why I sometimes wouldn't get any change in fuel depth when I adjusted the float tab. The fuel level was most likely above the gasket level & when I dropped the bowl, the fuel spilled out giving no apparent level change.

My new floats arrived in Fri so I swapped the float for a new one & adjusted it to the 'seam level is off'.

Put my jar against the float bowl flange & turned the fuel on.

This time the fuel almost overflowed but the float shut it off just in time.

Interesting...

Could I use this method for setting fuel level wrt jet stock?

Maybe but it would be an immense pain; the fuel level is so close to the float bowl flange that it doesn't take much to start spilling fuel everywhere & screwing up the reading. One way would be to find a wide mouthed shallow jar so that I put the whole carb body in it & rest the main jet on the jar's bottom.

What it does is put paid to the idea of a clear float bowl. What would be the use if the correct fuel level is at or above the float gasket flange? Unless the carb rake is such that there is a pocket of air in the rear of the float bowl to give a relative fuel level. Maybe not dead but only one foot in the grave...

So...

Put the float bowl on & filled it then VERY carefully removed it. Fuel was dead on my '24mm' reference mark.

Again, interesting...

Wonder how un-buoyant the old float is...

Finished the job, rough tuned the carbs took it for a ride (yes 10 km) & rechecked the carb tune. The idle balance hadn't change but the rpm had gone up 500 rpm. There is a small differential vacuum split that occurs when the throttles are opened but the split doesn't change up to 4k rpm.

With the old float, the would be a vacuum split when the throttles were opened which would match at 4k rpm, where it was matched, then split the other way as the throttle was opened beyond 4k rpm.

The bike is still a bit doggy in the needle jet range but a rocket when the main jets kick in.

Think I'll change the RH float before I go after which carb is the offender.

For those at home keeping score, I have access to a very precise scientific scale: good to 0.01gms. My new floats both came in at 12gms (12.00gms if you want the non ISO trailing zeros). My old LH float, dry but not dried out, came in at 12.9gms.

A bit of a head scratcher that 7.5% change in mass could make such a difference. But then again, if I've done my maths correctly, that comes out to a 0.4mm difference in fuel depth in the unmounted fuel bowl & substantially more when the bowl is in place & the floats, jets stock & other bits are consuming bowl volume.

Long winded but I got nothin' else to do with my (temporary) gimpy leg.
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Old 06-21-2013, 10:28 PM   #33
Plaka
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Quote:
Originally Posted by rustygardhouse View Post
So I tried the white lightning jar as a float bowl idea...
/snip.
Look at the height of the overflow standpipe in the bowl. The fuel cannot rise above this without pissing out. Make sure the pipe is clear. That is max fuel height---in fact is is above max fuel height, you need to leave some room for sloshing.

Anything in the bowl like the jetstock only displaces volume. no effect on height.

It's the density, volume and contour of the floats that matters, not the mass.


I mentioned it before; the float setting drill (make flange parrallel w/ body. etc) is crude. Guess why?
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Old 06-22-2013, 10:00 PM   #34
rustygardhouse OP
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Alrighty then...

Changed the RH float today. For those at home, new float 12gms, old float 14.2gms (dry but not dried out).

That surprised me so much I rechecked the level & zero of the scale. Got the same reading.

Wow!

Set this float with the 'level is off' method.

Rough balance the carbs, cleaned the plugs & went for a ride. The bike ran like it was too lean in both needle & main jets.

Came home & cut both plugs which showed both sides were lean. Yes, I'm back to cutting plugs to gauge mixture. Cleaned the plugs & reinstalled them.

Adjusted both carb floats to raise the level in the float bowls. It was a tiny tweak to both tabs.

Went for a ride & the bike performed better. A rocket on the main jets but still a little doggy in the needle jet.

All this careful tracking has shown that there could be two sources of this: one carb leaner that the other or the carbs are out of balance.

Cut the plugs. The RH looks fine but the LH might be a bit lean. Cleaned the plugs & reinstalled them.

Checked the carb balance at 4k rpm & sure enough the LH carb was lagging the RH. Rebalanced the carbs at 4k rpm.

Lesson learned? Yes the manual is correct: the 'floats level off' is only a starting point & the floats, as in my case, may need further tweaking to get them running correctly.

At this point I called it a day & I'll have another run at it next weekend.

WARNING!!!WARNING!!!WARNING!!!

SCIENCE CONTENT

The carb floats are a production item probably made by a stamping press for the metal bits & an injection mold for the foam bits.

I make this assumption because of uniformity of the weight of the floats.

So it is also reasonable to assume that the floats have the same volume which means that floats of equal weight displace equal volumes. Heavier floats displace more because they have a higher density. Conversely, lighter floats displace less because they are, yes, less dense.

In a closed system with a free surface, the extra fluid displaced by the denser float has to go someplace so the fluid level goes up.

Skeptical?

Go to your handy in home float bowl & float simulator system: your kitchen sink with a flat bottom Tupperware container.

Fill the sink half full of water & float the Tupperware container in the water.

Measure, mark, hold your thumb at the current water level.

Remove your Tupperware container & change its density by adding a bunch of silverware inside. Return your container to the sink.

Yes, since it now the same volume but more dense, it needs to displace more water to float which reveals itself by the water level in the sink rising above the old 'less dense' mark.

So goes it with floats.

A change in mass of bodies with near identical volume means that a mass of fluid equal to the difference in mass between the bodies needs to get out of the way. In a closed free surface system, the only thing the fluid can do is change height. I've got a decent idea of the float bowl area & the density of the fuel so it's fairly easy math to figure out how much the additional mass raises the fuel level.

If you are REALLY keen, you can now simulate the jet stock by sticking something in the sink to reduce the area of the free surface. & repeating the experiment.

Same displacement mass, same density of fluid, less area to accommodate the change, higher level of change.

Still don't believe me?

You can demonstrate the same thin with a piece of balsa wood & teak of identical volume & put them in a glass of water. Balsa new float, teak old float.

Just to fry your brain a bit more, as a cargo ship is being loaded, the ocean level is going up. Just a bit but it is.

END OF SCIENCE CONTENT
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Old 06-22-2013, 10:47 PM   #35
ME 109
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Bet you can't make a longer post Plaka.
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Old 06-23-2013, 01:57 AM   #36
Plaka
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Originally Posted by ME 109 View Post
Bet you can't make a longer post Plaka.
My post #29 is 763 words and 3362 non-space characters with a character/word ratio of 4.41

rustygardhouse' post #34 is merely 681 words and 2947 non-space characters with a character/word ratio of 4.33

I don't think I'm the lightweight here...

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Old 06-23-2013, 02:27 AM   #37
Plaka
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Quote:
Originally Posted by rustygardhouse View Post
Alrighty then...

Changed the RH float today. For those at home, new float 12gms, old float 14.2gms (dry but not dried out).

That surprised me so much I rechecked the level & zero of the scale. Got the same reading.

Wow!

Set this float with the 'level is off' method.

Rough balance the carbs, cleaned the plugs & went for a ride. The bike ran like it was too lean in both needle & main jets.

Came home & cut both plugs which showed both sides were lean. Yes, I'm back to cutting plugs to gauge mixture. Cleaned the plugs & reinstalled them.

Adjusted both carb floats to raise the level in the float bowls. It was a tiny tweak to both tabs.

Went for a ride & the bike performed better. A rocket on the main jets but still a little doggy in the needle jet.

All this careful tracking has shown that there could be two sources of this: one carb leaner that the other or the carbs are out of balance.

Cut the plugs. The RH looks fine but the LH might be a bit lean. Cleaned the plugs & reinstalled them.

Checked the carb balance at 4k rpm & sure enough the LH carb was lagging the RH. Rebalanced the carbs at 4k rpm.

Lesson learned? Yes the manual is correct: the 'floats level off' is only a starting point & the floats, as in my case, may need further tweaking to get them running correctly.

At this point I called it a day & I'll have another run at it next weekend.

WARNING!!!WARNING!!!WARNING!!!

SCIENCE CONTENT

The carb floats are a production item probably made by a stamping press for the metal bits & an injection mold for the foam bits.

I make this assumption because of uniformity of the weight of the floats.

So it is also reasonable to assume that the floats have the same volume which means that floats of equal weight displace equal volumes. Heavier floats displace more because they have a higher density. Conversely, lighter floats displace less because they are, yes, less dense.

In a closed system with a free surface, the extra fluid displaced by the denser float has to go someplace so the fluid level goes up.

Skeptical?

Go to your handy in home float bowl & float simulator system: your kitchen sink with a flat bottom Tupperware container.

Fill the sink half full of water & float the Tupperware container in the water.

Measure, mark, hold your thumb at the current water level.

Remove your Tupperware container & change its density by adding a bunch of silverware inside. Return your container to the sink.

Yes, since it now the same volume but more dense, it needs to displace more water to float which reveals itself by the water level in the sink rising above the old 'less dense' mark.

So goes it with floats.

A change in mass of bodies with near identical volume means that a mass of fluid equal to the difference in mass between the bodies needs to get out of the way. In a closed free surface system, the only thing the fluid can do is change height. I've got a decent idea of the float bowl area & the density of the fuel so it's fairly easy math to figure out how much the additional mass raises the fuel level.

If you are REALLY keen, you can now simulate the jet stock by sticking something in the sink to reduce the area of the free surface. & repeating the experiment.

Same displacement mass, same density of fluid, less area to accommodate the change, higher level of change.

Still don't believe me?

You can demonstrate the same thin with a piece of balsa wood & teak of identical volume & put them in a glass of water. Balsa new float, teak old float.

Just to fry your brain a bit more, as a cargo ship is being loaded, the ocean level is going up. Just a bit but it is.

END OF SCIENCE CONTENT
Sadly, it is not a static system but a dynamic one. The buoyancy of the float is compensated for by the setting of the tab that contacts the valve. A more buoyant float gets the tab adjusted down, a less buoyant one gets it adjusted up. So you get the same cutoff level with either one.


I had a teacher in highschool with a strongly rhetorical lecture style. He would ask some "unanswerable" question, pause for the moment of silence, then answer the question himself, thus structuring his lecture. Except I would sit there and answer the questions. I had read every National Geographic ever printed, most of the Automobile Quarterlies and Scientific American from about age 10 on. And a lot of fiction. And I still had good retention.
Well one day he figured he was safe. He drew a figure on the board and asked what it was. I answered that it was the loading mark diagram painted on the bows of big ships showing the max loading (by waterline) for various seasons and latitudes. He just looked at me and didn't say a word. I was a pretty annoying kid.

But just to fry your brain, you have neglected that the level in a vessel depends on the shape at any given volume. A gallon of margarita mix in a broad pan has a lower level than the same gallon in a slender column.

Combine this with plate tectonics and you see that the ocean doesn't rise a bit when a ship is loaded. The increased pressure on the oceanic plates from the greater mass of the ship, combined with the decreased pressure on the terrestrial plates from the transfer of the weight from land to ship, causes the oceanic plates to move apart and impinge on the terrestrial ones. The vessel becomes bigger and can hold a greater volume for a given level. So the water does not rise.


BTW, are you doing those plug chops in your driveway?

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Old 06-23-2013, 02:38 AM   #38
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What if the ship was sitting on the bottom when they loaded it? (tide was out sorta thing)
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Old 06-23-2013, 02:54 AM   #39
Plaka
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What if the ship was sitting on the bottom when they loaded it? (tide was out sorta thing)
Then it would break in pieces. The hull is barely self supporting...it needs a cradle and even more so when loaded. Sinking in the mud enough might save it, but then it won't have the buoyancy to float off.

Lake superior is very shallow---500-1300', compared to the ocean at over 30,000 ft. Yet it has a long enough fetch to catch lots of wind. The result is very quick, tall and steep waves. Deadly to the huge ore carriers in a storm. Head into the waves and you get high centered and the hull snaps, go broadside and they come over and swamp you. Stuff of songs...

At any rate, if you move cargo from one dock to another, there is no change on the pressure exerted on the land. If you move it from a dock to a grounded ship, same difference. If the tide then comes in and floats the ship off it is the same as loading the floating ship, the water is taking the pressure.
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Old 06-23-2013, 03:04 AM   #40
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That's all very well, but I was asking the question in relation to the tectonic plates, get my drift?
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Old 06-23-2013, 03:19 AM   #41
Plaka
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That's all very well, but I was asking the question in relation to the tectonic plates, get my drift?
Probably depend on the port. Oakland and Sacramento both have huge sea going ports. But Oakland is on all the fault lines.
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