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Carbs and Fuel System
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post #1 of 20 (permalink) Old 03-15-2014, 01:30 AM Thread Starter
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Zen Carburation.

A long read through the carburetor section recently,revealed some interesting facts,courtesy of the Professor.
The fact that air is thicker at low altitude,and thinner at high altitude is a given fact. Demonstrated by Fighter pilots at extreme altitude, and their piped oxygen to maintain consciousness.

This then means that with thicker or more air, at"low altitude" requires more fuel to keep the ratio's balanced.
Then with thinner air or less air at "High Altitude" we require less fuel, to achieve the balance ratio.
That all being understood, my question is.

Thick air should increase vacuum, and thin air alternately should decrease vacuum. If carbs are set well, at either end of the scale, does the vacuum, automatically change the mixture to satisfactory percentage.
I've found my bikes always seem to go better at night, is this because cool dense air makes more vac and draws more fuel,or is it because thicker air provides more air to burn a rich fuel mix better?

Who walks into the Lions Den, and comes out alive?
The Lion!
12 inch apes
1986 A3 series 750
Slash cut stainless mufflers
170 rear tyre
Custom cyane blue paint, wheels included
Relocated regulator rectifier
Solo mod
Stainless washable oil filter
Six pack rack
LED indicators and flasher unit.
Replaced CDI
Coasters
Penrite 10/50
Oil pressure hot at 1000 rpm 20 psi, 4000 rpm 60 psi
Shows 67000 kms
Jets 38 idle Mains 120 changed to 40 idle 135 main.
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post #2 of 20 (permalink) Old 03-15-2014, 01:45 AM
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Quote:
Thick air should increase vacuum, and thin air alternately should decrease vacuum. If carbs are set well, at either end of the scale, does the vacuum, automatically change the mixture to satisfactory percentage.
I've found my bikes always seem to go better at night, is this because cool dense air makes more vac and draws more fuel,or is it because thicker air provides more air to burn a rich fuel mix better?
You are right on track... another thing about cooler more dense air is it allows for better atomization of the oxygen with gasoline, resulting in a better burn.
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post #3 of 20 (permalink) Old 03-15-2014, 08:19 AM
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Also, the denser the air, the more fuel it can draw from the carb. remember that carbs dont pump fuel into the air stream like fuel injection (with the exception of accelerator pump circuits and such that we dont have in our carbs).

here is a video of basically how our CV carbs work

http://www.youtube.com/watch?v=wyspAHrMbb8
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post #4 of 20 (permalink) Old 03-24-2014, 07:48 AM Thread Starter
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Here is another question,how far out of round does an emulsion tube exit, get, before it becomes a problem,mine are about 10 000 metric,and that being said, what effect would this have on over all running?

Who walks into the Lions Den, and comes out alive?
The Lion!
12 inch apes
1986 A3 series 750
Slash cut stainless mufflers
170 rear tyre
Custom cyane blue paint, wheels included
Relocated regulator rectifier
Solo mod
Stainless washable oil filter
Six pack rack
LED indicators and flasher unit.
Replaced CDI
Coasters
Penrite 10/50
Oil pressure hot at 1000 rpm 20 psi, 4000 rpm 60 psi
Shows 67000 kms
Jets 38 idle Mains 120 changed to 40 idle 135 main.

Last edited by Big Nick; 03-24-2014 at 08:14 AM. Reason: Measure.
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post #5 of 20 (permalink) Old 03-24-2014, 12:29 PM
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Quote:
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an emulsion tube exit,
Define it further. The pressed in air jets?
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post #6 of 20 (permalink) Old 03-24-2014, 06:41 PM
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We who reside in the "snow belt", have found out the bike runs better when its colder out....that dont help the fingers that turn green though, lol....



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post #7 of 20 (permalink) Old 03-24-2014, 09:30 PM Thread Starter
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Toes either, and as it pours rain here at present,my toxic old ute looks more valuable than ever.

Who walks into the Lions Den, and comes out alive?
The Lion!
12 inch apes
1986 A3 series 750
Slash cut stainless mufflers
170 rear tyre
Custom cyane blue paint, wheels included
Relocated regulator rectifier
Solo mod
Stainless washable oil filter
Six pack rack
LED indicators and flasher unit.
Replaced CDI
Coasters
Penrite 10/50
Oil pressure hot at 1000 rpm 20 psi, 4000 rpm 60 psi
Shows 67000 kms
Jets 38 idle Mains 120 changed to 40 idle 135 main.
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post #8 of 20 (permalink) Old 03-24-2014, 09:38 PM
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Yer goin into Autumn now, aint ya ?....



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post #9 of 20 (permalink) Old 03-24-2014, 10:29 PM
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Quote:
Originally Posted by wmsonta View Post
Define it further. The pressed in air jets?
Emulsion tube is the bit with several holes around it that the jet (one hole) screws into. No idea on the specs. I'd check my parts while I'm doing this rejet but I doubt my micrometer is accurate enough for a reliable reading on that.

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post #10 of 20 (permalink) Old 03-24-2014, 10:33 PM
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Quote:
Originally Posted by Hexadecimus View Post
Emulsion tube is the bit with several holes around it that the jet (one hole) screws into. No idea on the specs. I'd check my parts while I'm doing this rejet but I doubt my micrometer is accurate enough for a reliable reading on that.
Yes, I know that. What is an emulsion tube exit? One that could elongate an 'exit'?
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