oil ratio

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Assume the oil doesn't burn. Assume you need say 13 to 1 air to gas for perfect combustion (both of these assumptions are slightly incorrect...;))

If your oil is 2% of your gas (50:1 mix), then you'll need to decrease your air (or increase the gas) by 2% of 13:1.. Change to 32:1.. you do the math..
 
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the way I do the math more oil will lean the air fuel ratio but I,ve been wrong before. anyway me and a friend were disagreeing about it.
 
It is my understanding from conversations with two different Dolmar dealers that more oil in the fuel mix will lean the saw. If running a mix heavier that 50:1, the carb will need to be richened up a bit.:chainsaw:
 
It is my understanding from conversations with two different Dolmar dealers that more oil in the fuel mix will lean the saw. If running a mix heavier that 50:1, the carb will need to be richened up a bit.:chainsaw:
that makes sense to me. If the oil doesn,t combust it will displace some of the fuel the air stays the same therefore the mixture is leaner.
 
But isn't it different than an air leak lean condition?

Interesting.
But I wouldn't consider it the same lean condition that occurs when you turn in your mixture screw.
You turn in the mixture screw and you've reduced the oil and the gas both.

If you up raise your oil ratio, you haven't increased air. Just added oil and reduced gas. Oil being the lubricant; it may have less power marginally but not less lubrication as would a classic air leak, no?
-br



It is my understanding from conversations with two different Dolmar dealers that more oil in the fuel mix will lean the saw. If running a mix heavier that 50:1, the carb will need to be richened up a bit.:chainsaw:
 
14.7 is in-theory the perfect ratio.. but... to quote Wiki...

"Naturally Aspirated engines powered by octane, maximum power is frequently reached at AFRs ranging from 12.5 - 13.3:1 or λ of 0.85 - 0.901."

Does it have to do with how well the fuel is suspended in the air?
 
Interesting.
But I wouldn't consider it the same lean condition that occurs when you turn in your mixture screw.
You turn in the mixture screw and you've reduced the oil and the gas both.

If you up raise your oil ratio, you haven't increased air. Just added oil and reduced gas. Oil being the lubricant; it may have less power marginally but not less lubrication as would a classic air leak, no?
-br
Dammit, just when I thought I was catchin on, now I gotta start all over.
 
Does it have to do with how well the fuel is suspended in the air?

I was wondering sort of the same thing. Does it have to do with the fact that the tolerances can't be absolutely perfect, and or does gravity have some sort of effect? I think it's getting to be time to concentrate more on drinking than thinking.
:cheers:
 
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