Okay lets clear this up please

Jaybird

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#2
More oil means that there is less gas in a given space. Also more oil increases the viscosity(or makes it thicker), which means the mixture flows through the jet orifice at a slower rate, leaning the condition.
 
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#3
Originally posted by Jaybird
Also more oil increases the viscosity(or makes it thicker), which means the mixture flows through the jet orifice at a slower rate, leaning the condition.
For the 500th time, it has nothing to do with viscosity. :(
Jets meter by volume, and for a given volume being passed there is less gas when more oil is present. The effects of viscosity in this case are too minor to be relevant.
 
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#4
C'mon, Rich!

Man, when I saw the post before Rich's this morn, I was tempted to "correct"
the obvoius misinformation, but I figured Richs response would be worth a laugh on this one--Cmon, Rich, get a cup of coffee in ya, and try again!! :) I have for years cringed when I hear people talking about the "richer" or "leaner" fuel /oil mixture. I will attempt to explain it in the most non-confusing, basic of ways:The terms "rich" or "lean" are directly relevant to the FUEL to AIR ratio--oil (as in 2 stoke) is a 3rd factor in the equation!--For example: a 32 to 1 mix will be leaner than a 40 to 1 mix because there is less FUEL, because it has been displaced by the additional 2 stroke oil.
 
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#5
Re: This is not Advanced Tech. Rich

Originally posted by Yamamoto


Calm down a tad......I get a bit bored with the simple topics but thats why there is general topic and YOUR advanced topic.
I'm not bored with the topic(OK, maybe a little :) ) , but I do get annoyed with the fact that everytime the topic comes up this viscosity nonsense gets dragged in to muddy things up. When misinformation gets repeated enough times it turns into fact for some people. It's the hallmark of psuedo-tech advocates worldwide.

Jaybird summed it up perfectly with
More oil means that there is less gas in a given space.
He unfortunately got sucked into the undertow of viscosity , and veered into MXA territory:eek:
 

a454elk

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#6
Wow, all I know is that the higher the ratio for example, 50:1 gives you less oil and the lower gives you more oil. Less oil, chance of seizing due to non lubrication (don't try this at home). More oil, chance of fouling and spooging. I found that at a higher elevation, the more oil seems to casue fouling due to the combo of richer fuel and no air! Good luck. I run at 35:1, seems fine.
Elk
 
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#7
Maybe when I ever get the chance to go to a dirtweek rich can explain this to me, but I still see it like this
for you out there who think less oil means richer, run your bike at 500:1 and tell me how rich it runs!:p
Ill stick to my 40:1 thanks!

OR run your bike at 5:1 and tell me how lean it runs!
 

MikeT

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#8
Originally posted by Rich Rohrich


For the 500th time, it has nothing to do with viscosity. :(
Jets meter by volume, and for a given volume being passed there is less gas when more oil is present. The effects of viscosity in this case are too minor to be relevant.
Too minor to be relevant.... Thats the answer I needed. I knew that the leaner fuel/air mix was because of a lower percentage of fuel, because of more oil, but I didn't know to what extent viscosity played. Rich I'll take it as fact that it doesn't have that much of an effect but I can't really agree with you when you say that jets meter by volume. Correct me if I'm wrong but since they (jets) are an orifice, they meter flow. "Q" or the quantity of fuel is a product of area x velocity. Q=av. One main jet is different from another because of its orifice diameter, right? If you have a smaller a (area) you will get a lower Q or quantity of fuel. This is all saying that the velocity remains the same (which you pointed out should stay the same).

Does this sound correct? If not just point out the right direction.

Mike
 

MikeT

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#9
Originally posted by John.T
Maybe when I ever get the chance to go to a dirtweek rich can explain this to me, but I still see it like this
for you out there who think less oil means richer, run your bike at 500:1 and tell me how rich it runs!:p
Ill stick to my 40:1 thanks!

OR run your bike at 5:1 and tell me how lean it runs!

You are dealing with extremes and you cant really do that. No bike will run at 5:1 and no 2 stroke will run for long at 500:1. We aren't talking about extremes like that, only small variations in mix ratios. Like 26:1 being a lean mix and 50:1 being a rich mix. A bike will run in both mixes, but will you get the results you want? I believe that my parts will last longer at 26:1 than at 50:1 with the way I ride. I also happen to get less if not any spooge running at 32:1 whereas I used to get a fair amout of spooge at 50:1.

That's all we are saying.
 

Wolf

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#10
Originally posted by MikeT

I also happen to get less if not any spooge running at 32:1 whereas I used to get a fair amout of spooge at 50:1.
All of it makes sense except for that. I speak of my experience and mine only, but I have played around with 32:1,40:1,50:1 and one thing is pretty clear to me: 32:1 produces a lot more spooge than 50:1.
 

Casper250

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#11
I think the confusion comes from the wording of how things are being described. Kind of like gear ratios,when you use a lower gear ratio, you re actually rasing the numerical ratio. ex.10 to 1 is a lower ratio then 5 to 1.

Picture a glass of water, wich will represent gas. If you fill it to the top and took a rock, which will represent the oil, and droped it into the cup, the rock will displace the water and make some overflow. the bigger the rock, the more water that it will displace.

A ratio of 32 to 1 is a ratio that has more oil in the mixture then a ratio of 50 to 1 so it will displace more of the gas.

Now a motor only needs air and fuel to run on, the oil just provides lubrication. Since the oil is taking up some of the volume that normally would be gas, there is less gas to mix with the air. This is the lean condition that people are refering to.

Now it might be a little confusion in that when you add more oil, THE FUEL is RICH in oil, but the mixture causes a lean condition in the burning of the fuel.

Hope i didn't confuse you more....
 
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#12
Originally posted by MikeT
Rich I'll take it as fact that it doesn't have that much of an effect but I can't really agree with you when you say that jets meter by volume.
I must be missing something. You described a change in volumetric flow based on a relative change in orifice size . Where exactly do you disagree ? :)

Jets meter by volume but air/fuel ratio is a function of fuel MASS relative to air MASS trapped in the combustion chamber. There isn't a 1 to 1 relationship.

With enough information about the variables and enough math it is possible to determine mass flow through a jet but most jetting charts and formulas are based on volume and total fuel mass is implied .
 
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#13
Originally posted by John.T
Maybe when I ever get the chance to go to a dirtweek rich can explain this to me
I try not to suffer fools out here but I make it a point not to do it in real life. You'll have to find someone else to wade out there and save you from drowning in your personal sea of ignorance.:silly:
 

motometal

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#14
454, did you read any part of this thread?

The velocity thru an orifice will be relative to mass AND viscosity of the fluid pulled thru it.

Maybe you are right, Rich on the viscosity thing...could you (or have you) set up a simple test? All you need is a source of vacuum, an orifice, and a way to measure volume passed thru the orifice.
 
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#15
Why don't you stick THIS through your orifice! :eek:

Sorry couldn't resist. Rich is spot on as usual. Some of you might want to review your junior high physics and mathmatics.

:D