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Premix ratio vs. fuel/air ratio ?
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[QUOTE="Trailryder42, post: 966248, member: 17282"] I hope this is the right forum to ask this. I've been having a discussion with a buddy about premix ratios for 2 stroke engines and their effect on the fuel/air ratio. It is my understanding that when we talk of richness or leaness, we're talking about the amount of "fuel" in the fuel/air ratio. Correct? A premix ratio of 32:1 has more oil in it than a ratio of, say, 40:1. Correct? It is my understanding that an engine can be fine tuned/dialed in for a given situation by altering the premix ratio. Going from a premix ratio of 32:1 to that of 40:1 means the engine is getting less oil and more atomized fuel from the premix charge from the carb, making the fuel /air ratio richer; and visa versa if you went from a 40:1 premix to a 32:1 ratio, more oil displacing fuel in the mix, making for a leaner fuel/air ratio. Is this correct? Thing is, alot of my buds use the terms rich and lean to describe the air/fuel ratio as to how much oil there is in their premix ratios. 32:1 being richer than 40:1. When they foul a plug it's because they're too rich(too much oil). And I agree to a point. The engine can utilize only so much oil from a premix in the combustion process, depending on premix ratios and jetting. It's the amount of atomized, or raw fuel for that matter, that the engine is getting and is able to utilize in the combustion process that determines how the oil in the premix is utilized. Whether it is burned and how completely. Is this correct? Because it's not the volitility of the oil in the premix that creates an ignitable mixture with air for the combustion process, it's the fuel. Finally, (SHEESH!, you say), you will foul a plug when you either have more oil than the engine can utilize or the fuel/air ratio is too "rich"(more fuel than the engine can burn, too saturated. In this scenario you actually have a combination of fuel/oil fouling). At the beginning I said the terms "rich" and "lean" were used to describe the amount of "fuel" in the fuel/air ratio. What other/separate terms to use to describe the under or over-abundance of "oil"? Thanks [/QUOTE]
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Premix ratio vs. fuel/air ratio ?
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