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Old 06-16-2013, 01:50 PM   #16
Plaka
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Quote:
Originally Posted by 190e View Post
This is a really interesting thread - at least when it sticks to talking about carbs.


Rusty

When you say the carbs are very sensitive to fuel level I always think that the most important thing is that the levels are as equal as possible for both carbs. So from your observations just how close to equal do they need to be. 1mm or less ?

Also from the same observations did you notice that the sensitivity to level varied at different throttle openings ? In other words if you have a level difference between the carbs where does it have the biggest impact.


For what It's worth I think 24mm is a touch high and tend towards 22 - 23mm


Supershaft.

It's quite a few years back but you used to say the level was 22/32nds on your machinist rule which = 22.2mm

and ME 109 quipped:

28/32 isn't being too exact but 56/64" is !!
I like to set mine at 7/8"


Interesting topic carb levels.

You have a problem talking about boobies (esp. with pictures)?

I'd get the levels equal for tuning purposes on the stand. Out on the road they are going to be jumping around so much that it would take some fine and fancy statistics to tell what they are.

It occures to me that the really easy way to set very accurate levels is to determine where the top surface of the fuel is with respect to some reference on the jet stack. Then, bowl off, just hold a small glass dish under the carb, and touching it to hold steady, turn on the gas and see where the top of the fuel is with respect to your mark when the float shuts it off.

You still have a chicken and egg problem to determine where the level "should" be when the float is "correctly" adjusted. I would go by what makes your jetting work well. You can tweak the jetting by tweaking the fuel height.

What matters might be worth determining. Compute how much of a change in fuel depth will change the delivery pressure some arbitrary amount. You can look up that calculation.

Then take a guess at how much the depth changes as the fuel sloshes around.

lastly measure the depth in the bowl and with a bit of arithmetic compute the percentage change in pressure mm/mm with depth.

Compare that with your guess on the slosh pressure change to get an expected variation in pressure.

Don't sweat setting the fuel depth to a tighter tolerance that that expected variation. You're gilding a toad.


One procedure for setting the float is to run fuel into a can and lift the float with your finger until it just shuts off. Float seam should be parallel with carb bottom. This does not account for variation in float buoyancy but it's good enough and quite consistent otherwise..
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Old 06-16-2013, 03:25 PM   #17
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Quote:
Originally Posted by Plaka View Post
You have a problem talking about boobies (esp. with pictures)?

I'd get the levels equal for tuning purposes on the stand. Out on the road they are going to be jumping around so much that it would take some fine and fancy statistics to tell what they are.

It occures to me that the really easy way to set very accurate levels is to determine where the top surface of the fuel is with respect to some reference on the jet stack. Then, bowl off, just hold a small glass dish under the carb, and touching it to hold steady, turn on the gas and see where the top of the fuel is with respect to your mark when the float shuts it off.

You still have a chicken and egg problem to determine where the level "should" be when the float is "correctly" adjusted. I would go by what makes your jetting work well. You can tweak the jetting by tweaking the fuel height.

What matters might be worth determining. Compute how much of a change in fuel depth will change the delivery pressure some arbitrary amount. You can look up that calculation.

Then take a guess at how much the depth changes as the fuel sloshes around.

lastly measure the depth in the bowl and with a bit of arithmetic compute the percentage change in pressure mm/mm with depth.

Compare that with your guess on the slosh pressure change to get an expected variation in pressure.

Don't sweat setting the fuel depth to a tighter tolerance that that expected variation. You're gilding a toad.


One procedure for setting the float is to run fuel into a can and lift the float with your finger until it just shuts off. Float seam should be parallel with carb bottom. This does not account for variation in float buoyancy but it's good enough and quite consistent otherwise..
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Old 06-16-2013, 04:26 PM   #18
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Quote:
Originally Posted by Plaka View Post
You have a problem talking about boobies (esp. with pictures)?

I'd get the levels equal for tuning purposes on the stand. Out on the road they are going to be jumping around so much that it would take some fine and fancy statistics to tell what they are.

It occures to me that the really easy way to set very accurate levels is to determine where the top surface of the fuel is with respect to some reference on the jet stack. Then, bowl off, just hold a small glass dish under the carb, and touching it to hold steady, turn on the gas and see where the top of the fuel is with respect to your mark when the float shuts it off.

You still have a chicken and egg problem to determine where the level "should" be when the float is "correctly" adjusted. I would go by what makes your jetting work well. You can tweak the jetting by tweaking the fuel height.

What matters might be worth determining. Compute how much of a change in fuel depth will change the delivery pressure some arbitrary amount. You can look up that calculation.

Then take a guess at how much the depth changes as the fuel sloshes around.

lastly measure the depth in the bowl and with a bit of arithmetic compute the percentage change in pressure mm/mm with depth.

Compare that with your guess on the slosh pressure change to get an expected variation in pressure.

Don't sweat setting the fuel depth to a tighter tolerance that that expected variation. You're gilding a toad.


One procedure for setting the float is to run fuel into a can and lift the float with your finger until it just shuts off. Float seam should be parallel with carb bottom. This does not account for variation in float buoyancy but it's good enough and quite consistent otherwise..
I like my method much mo'
And, you must have slow RS's over there Plaka.
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Old 06-16-2013, 06:40 PM   #19
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Interesting thread.

I can picture big money to be made by producing translucent Bing float bowls with little graduations down the side, so you don't even need to remove them to get your measurement. Surely someone out there has access to a 3D printer..
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Old 06-16-2013, 06:41 PM   #20
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FWIW, the Bing manual states:

1. Tilt carburettor past horizontal approximately 15 degrees or an amount causing float pointer to "lightly touch" float needle spring-plunger (or ball) without depressing plunger into needle.
2. Increase or decrease pointer-to-hinge angle with a thin blade screwdriver until top surface of float element is parallel with base of carburettor. Both plastic elements must also be parallel with each other; if not, carefully twist elements to obtain correct parallelism (excessive twisting force can separate plastic from metal hinges).
3. Repeat above steps 1 and 2 until desired results are obtained.

But then, who would follow the Bing manual; where's the fun in that? YMMV.
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Old 06-16-2013, 07:53 PM   #21
Plaka
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Originally Posted by Stan_R80/7 View Post
FWIW, the Bing manual states:

1. Tilt carburettor past horizontal approximately 15 degrees or an amount causing float pointer to "lightly touch" float needle spring-plunger (or ball) without depressing plunger into needle.
2. Increase or decrease pointer-to-hinge angle with a thin blade screwdriver until top surface of float element is parallel with base of carburettor. Both plastic elements must also be parallel with each other; if not, carefully twist elements to obtain correct parallelism (excessive twisting force can separate plastic from metal hinges).
3. Repeat above steps 1 and 2 until desired results are obtained.

But then, who would follow the Bing manual; where's the fun in that? YMMV.
Especially when they use weasel words like "approximately"!

I'm for dumping the fuel into a graduated cylinder and reading the volume to 1/4cc.
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Old 06-16-2013, 09:31 PM   #22
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Originally Posted by Plaka View Post
Especially when they use weasel words like "approximately"!

I'm for dumping the fuel into a graduated cylinder and reading the volume to 1/4cc.

The volume of the float bowl means nothing, the level is everything. Think about it.
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Old 06-16-2013, 09:43 PM   #23
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Originally Posted by crazydrummerdude View Post
Interesting thread.

I can picture big money to be made by producing translucent Bing float bowls with little graduations down the side, so you don't even need to remove them to get your measurement. Surely someone out there has access to a 3D printer..
Mallossi made clear bowls for dellorto phbg series carbs for scooter and moped tuners...... All the rage til the plastic shrank up and dumped a bunch o gas on top of the magneto.
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Old 06-16-2013, 10:50 PM   #24
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More info

So where to begin...

I didn't forget: with all the variation in the castings of the carb body & float bowl as well as the gasket & gasket compression, the marks are only a relative measure of fuel level so I can easily see the changes. The marks are adjusted so they actual read from the edge of the bowl down which removes casting variation in the depth of the bowl.

I tried to follow the Bing recommended method as well as Snowbum's lift the float method. Of the two I think Snowbum's is the better method. the thing that both of these methods depend on is floats of the same volume & buoyancy.

I just hate lying on my side trying to figure if some faint line on the float is level with the bottom surface of the carb body. I even used the float bowl bail to hold the float in position but to me it's just too inconsistent.

I'm running 'older' floats & they certainly are not the same volume. When set to the Snowbum method, there is a difference in the fuel level.

Yes, I have new floats on order... But if I can figure this out, I can make old floats work as well.

I also tried Snowbum's stick in the bowl with a notch & got tired of it.

When I read the marks, I place the bowl in the same place & in the same orientation to reduce variations from unlevel surfaces. Like I said, the marks aren't absolute but they do let me know how much I've changed the fuel level as I tweak the fuel level.

so the first thing I do is take two reference readings before I start playing with the level.

I really like the idea of a clear float bowl to see where the fuel level is wrt to the jet stock. This doesn't really have to mimic the bowl just its gasket profile. It could have scribe marks on its side for fuel level reference.

Some days it's fun to be a mech design eng ne aircraft mech ne logger. Give me a bit & I'll whip up a model.

Fuel level & performance...

The left carb is being a problem child. It was running lean though the needle & main jet. As I increased the fuel level by 1mm the needle jet came alive but the main is still way too lean 14s at the cross over, 17s at wot. Basically, the bike is running on the right cylinder.

One of the things that concerns me is that with the rake of the R65 carbs, the fuel level can get high enough that the idle ports are below the fuel level. I think I'm seeing this on the right side as the idle screw seems to have lost it's effectiveness.

Did I cover everyone's questions?

Here's a gotcha: When I got this bike a year ago, I had the shop lash the valves & check the timing. Well, in a fit of 'just in case' I thought I'd check the valve lash & timing.

Results?

Left exhaust was set to 0.012" but the rest were fine.

Can't find the timing mark with my timing light. The marks are there, I've repainted them with bright yellow nail polish but I can't see them. The mark I do see is ~60 away from the timing marks.

I'm wondering if the flywheel was put on one hole over the last time the clutch was done.

Anyone know if it's possible to install the flywheel one hole over?
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Old 06-16-2013, 11:13 PM   #25
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clear fuel level checker

here's my concept for a clear fuel level checker:

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Old 06-16-2013, 11:22 PM   #26
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Anyone know if it's possible to install the flywheel one hole over?
Sure is.
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Old 06-17-2013, 12:39 AM   #27
rustygardhouse OP
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well... CRAP!!!!
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Old 06-17-2013, 01:11 AM   #28
ME 109
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well... CRAP!!!!
Don't worry about it. Just make out like you're a non-conformist.
That's what I did.
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Old 06-17-2013, 10:29 PM   #29
Plaka
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Originally Posted by rustygardhouse View Post
So where to begin...

I didn't forget: with all the variation in the castings of the carb body & float bowl as well as the gasket & gasket compression, the marks are only a relative measure of fuel level so I can easily see the changes. The marks are adjusted so they actual read from the edge of the bowl down which removes casting variation in the depth of the bowl.

I tried to follow the Bing recommended method as well as Snowbum's lift the float method. Of the two I think Snowbum's is the better method. the thing that both of these methods depend on is floats of the same volume & buoyancy.

I just hate lying on my side trying to figure if some faint line on the float is level with the bottom surface of the carb body. I even used the float bowl bail to hold the float in position but to me it's just too inconsistent.

I'm running 'older' floats & they certainly are not the same volume. When set to the Snowbum method, there is a difference in the fuel level.

Yes, I have new floats on order... But if I can figure this out, I can make old floats work as well.

I also tried Snowbum's stick in the bowl with a notch & got tired of it.

When I read the marks, I place the bowl in the same place & in the same orientation to reduce variations from unlevel surfaces. Like I said, the marks aren't absolute but they do let me know how much I've changed the fuel level as I tweak the fuel level.

so the first thing I do is take two reference readings before I start playing with the level.

I really like the idea of a clear float bowl to see where the fuel level is wrt to the jet stock. This doesn't really have to mimic the bowl just its gasket profile. It could have scribe marks on its side for fuel level reference.

Some days it's fun to be a mech design eng ne aircraft mech ne logger. Give me a bit & I'll whip up a model.

Fuel level & performance...

The left carb is being a problem child. It was running lean though the needle & main jet. As I increased the fuel level by 1mm the needle jet came alive but the main is still way too lean 14s at the cross over, 17s at wot. Basically, the bike is running on the right cylinder.

One of the things that concerns me is that with the rake of the R65 carbs, the fuel level can get high enough that the idle ports are below the fuel level. I think I'm seeing this on the right side as the idle screw seems to have lost it's effectiveness.

Did I cover everyone's questions?

Here's a gotcha: When I got this bike a year ago, I had the shop lash the valves & check the timing. Well, in a fit of 'just in case' I thought I'd check the valve lash & timing.

Results?

Left exhaust was set to 0.012" but the rest were fine.

Can't find the timing mark with my timing light. The marks are there, I've repainted them with bright yellow nail polish but I can't see them. The mark I do see is ~60 away from the timing marks.

I'm wondering if the flywheel was put on one hole over the last time the clutch was done.

Anyone know if it's possible to install the flywheel one hole over?
Man, I don't want to harsh on ya or hurt your feelings, but you don't seem to get it.

The only thing that matters is the distance from the surface of the fuel to the opening in the main jet. if the bowl is six feet wide and 10 feet deep and cocked 20 degrees sideways, it all the same. Dimensions of the bowl, volume, perpendicularity to gravity, casting variations, color, creed, religion, marital satus or sexual orientation mean nothing. They have no effect on the distance from the surface of the fuel to the opening of the main jet.

So get rid of the bowl, O.K.? It's distracting you.

Never measure the correlate of something when you can measure the thing itself. if you want your motor to be well balanced and to run smoothly, measure that balance directly. Vacuum is not balance. Mixture is not balance. You toys/tools have good uses, but you are not using them for those. measure the power output of each side directly. It's rather simple to do.

So too with the distance betwen the surface of the ful in the and the openig of the jet. What you are really after is pressure but this is difficult enough to measure that you go for the correlate of height. And long as your fuel densities are pretty consistent your correlation coefficients will be strong. Atmospheric pressure cancels out BTW.

Putting little makrs on something merely reveals that you have never been a tradesman that knows how to do thing. I have been / am one, as well as a scientist, engineer, social worker and artist. However, to humor you, and because I am hurting your feelings anyway, I have made some marks on the carb body. I know how close the fuel can get to the body before it goes out the overflow tube (may height) and I know how far away it can be without uncovering thee idle jet and killing that circuit. (min height). So I knw the istance range for the marks. BTW, it can't flood out the idle ports in the venturi, they are above the overflow.

Just for you (and I mean that, this is why they are on the inside):



I could make those so they would have .01mm resolution. It's just an example so I don't care to. But they are engraved, marked and for real.

Now look what happens:



Such a fit!. Floats are totally free. The only reason it's glass is so you can see when the float shuts off. Your method is to hold the jar up and turn on the gas. pop the bail off first to get it out of your hair. When the float shuts off the gas, you turn off the petcock and lower the jar collecting whatever drains from the line without changing the high water mark on the body. Then lower the jar completely and read the high water mark. If you were a tradesman you would simply capture that mark rather than reading divisions. More accurate---but also sort of a trade secret.

jar is pretty deep and you are only interested in what is happening in the top half inch, so keep it pretty full.

The surface of the fuel is always level no matter what the jar does. The float always shuts off at the same point even if you wiggle or lower the jar during the test. This jar is a nice size because you can hold it against the carb bottom to steady it. And you can get them in any grocery store. And they have nice lids you can reuse.

Match the levels on both sides for starters. If you are way out on mixtures after that look for some other problem. Do not just sweep it under the rug by diddling the fuel levels.

Bob (snowbum) knows a great deal in a number of fields. He also knows shit in some of them. I like the guy personally, but I respect his limitations. I have not read his float setting stuff in recent memory nor have I recorded it. I suspect I started to read it once, realized this was something he was too clueless about, stopped and moved to something else.

if you are going to try the float-touches-needle-and-gives-monkey-joy position, you sit on a stool, pop the carb off without disturbing the cable and hold it at 45d. so you can see easily but the float won't swing too fast.


Good luck...Mr. Phelps.
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Old 06-18-2013, 11:21 PM   #30
rustygardhouse OP
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OK, you got me: I'm lazy & tried to get a less than ideal system to work.

Like I said, I like the idea of a clear float bowl so that I can see the fuel level wrt to the jet stock which is what really matters. which removes the condition of the floats from the equations.

Which means I like your shade tree mechanic approach with the white lightning jar.

Think I'll give this a try this weekend.

Thx!
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