Air Fuel Ratio

Here is a air fuel ratio chart to help wif tuning those carbies. Keep your afr at 10:1 for starting 12:1 for acceleration and 14.7:1 for the enviornment. Never go lower then 18:1 for economy or you will seize a lot of engines just from leaning and making too much heat.

REMEMBER the chart is AIR FUEL ratio and NOT PreMix ratio.

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But how can you measure this?

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exactly, i dont see how this is useful at all

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Handy if your running an air fuel meter. I wonder if the oil in the exhaust would foul up the oxygen sensor.

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I'm running about 8:1 or 9:1 in my car; in desperate need of a tune. Not recommened. I drive in my own personal smoke cloud.

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nice, tanks wari!

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Yes, oil does ruin oxygen sensors.

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thats pretty sweet. but two questions...

-does the fuel part of the ratio include the amount of oil in your fuel?... ooh now i read the fine print and it does not. bummer.

-Is there a way you can quantitize your fuel and air amounts on standard carburetors? Like make a ratio of the jet size (area of the jet hole) to the area of the air intake? Is it as simple as just, say, 1 sq mm (approximation for area of jet hole) to 1 sq inch (approximation for area of intake hole), or is there more complicated physics behind it than that? Like bringing in fluid dynamics and all that crazy shit. If thats the case then that seems like a lot of work.

Is there something more im missing to actually being able to use this chart? Nice work, however, and will be useful to someone who has the know how to use it!

Haha and by the way, did you come up with this stuff yourself? Youd be quite the scientist if you did.

good work,

-Steve

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The amount of oil in your gas makes up for about 1/700 of the final air fuel ratio, so I wouldn't worry about it displacing too much fuel.

As for the usefulness, it is very useful to understand the effects the of air/fuel ratio on running. The better you understand the process the more accurate your observations and guesses will be about your running condition.

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She is quite the scientist, and I only see her getting so intelligent, that she could change the whole world with it! She's also a sweetheart, so I won't continue and embarrass her anymore if I can help it.

My admiration keeps growing.

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ay dios mio! 300 somethin dollars for that guy! a bit more than im looking to spend... cool stuff tho wari.

oh and welcome back.. when did you get back anyways?

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yeah well it's a multi channel data logger. in addition to air/fuel you can get:

RPM

Cylinder Head Temperature

Exhaust Gas Temperature

Acceleration

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innovative ways to take your money. there are less expensive ways to check air fuel ratio that doesnt plug into a puter. save a couple of dollars using a special scribing instrument called a pen and a data collection medium called paper.

exhaust gas temperature gauge, heat temperature gauge, a tinytach and a air/fuel ratio gauge is less then $300

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If the usefullness of that chart isn't easily understood, then, well, I'm at a loss as how to describe that.....

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stoichiometry for dummies?

definitely for ME!

wari you gotta team up with the motomatic kids and get making stuff.

you also, i think, need a lab coat. ;)

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the chart isnt as useful as it can be until you can measure the exact fuel/air quantities goin thru your carb. Until you can do that that's all good qualitative observations, and will help you tune, but you cant use any of those ratios (accurately) until you can measure exactly how much of both fluids you have. or am i wrong?

and wari i know youre good, but youre telling me you can measure those quantities with just a pen and paper? please fill me in i'd like to be able to do the same. seriously.

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Quantitative research is the systematic scientific investigation of properties and phenomena and their relationships. The objective of quantitative research is to develop and employ mathematical models, theories and/or hypotheses pertaining to natural phenomena. The process of measurement is central to quantitative research because it provides the fundamental connection between empirical observation and mathematical expression of quantitative relationships

Scientific method look into it...

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ahh...

awkward grammar appalls a craftsman. a dada bard as daft as tzara damns stagnant art and scrawls an alpha (a slapdash arc and a backward zag) that mars all stanzas and jams all ballads (what a scandal). a madcap vandal crafts a small black ankh - a hand stamp that can stamp a wax pad and at last plant a mark that sparks an _ars magna_ (an abstract art that charts a phrasal anagram). a pagan skald chants a dark saga (a mahabharata), as a palpal cabal blackballs all annals and tracts, all dramas and psalms: kant and kafka, marx and marat. a law as harsh as a _fatwa_ bans all paragraphs that lack an A as a standard hallmark.

;)

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ok i'd better get to bed..

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wari: "innovative ways to take your money. there are less expensive ways to check air fuel ratio that doesnt plug into a puter. save a couple of dollars using a special scribing instrument called a pen and a data collection medium called paper.

exhaust gas temperature gauge, heat temperature gauge, a tinytach and a air/fuel ratio gauge is less then $300"

yes thanks ive heard of pen and paper. try writing shit down going 50. and maybe you can show us a way to check the air/fuel mixture. oh and it has to work well outside the 14.7:1 ratio that most O2 sensors are limited to.

but in all thanks for cutting and pasting off the internet and not giving any credit to the source. invaluable. meaning, no value. next time credit where it's due please. because maybe they have more too offer than you.

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im with matt and steve

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HEY.

how many of the kids that read this forum have engineering degrees?

i remember the first time i heard of stoichiometry, and i built a really nice rabbit that i bought from the guy who explained it to me.

i love this chart. i love the idea of documenting my motor's habits and tuning with empirical knowledge.

measurement is never a perfect or easy game, but if looking closer at your combustion doesn't help you then why hate on people who enjoy it and are trying to help everyone else?

think all the performance parts we love are built without any engineering?

i don't!

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srsly. I can go copy and paste off of the internet. Its not going to help anyone apply this information to a real life situation, which is what we're all trying to do here.

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i wrote 3 sentences there not just one or two.

_innovative ways to take your money. there are less expensive ways to check air fuel ratio that doesnt plug into a puter. save a couple of dollars using a special scribing instrument called a pen and a data collection medium called paper.

exhaust gas temperature gauge, heat temperature gauge, a tinytach and a air/fuel ratio gauge is less then $300_

i am trying to suggest you get the four gauges and do testing then write down the results. just get a afr gauge to check the ratio and use the heat probes to fine tune. run your engine at 1/4 1/2 3/4 and full throttle gauged by tach and have the mix heavy on the first quarter, full power from 1/4 thru 3/4 and towards econo at the top end. then you can run all day without seizing and make SERIOUS power.

ALSO

the uselessness of the chart i posted is in the eyes of the beholder. just keep throwing random stuff on your mopeds and hope that the last person that told you to put whatever on your ped had a little bit of a idea what they are doing and not just a suggestion to buy something caue it looks cool to have the sticker that comes wif it on your tool box. if you actually READ stuff you will learn that 2 stroke engines are not magic they are just thermodynamic converters that turn the released heat from combustion into mechanical energy. i thought the performance tuning was to help eachother learn how to get the best perfromance out of their peds and not as advertising for the latest most popular component based on some abstract visual cool rating.

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"i thought the performance tuning was to help eachother learn how to get the best perfromance out of their peds and not as advertising for the latest most popular component based on some abstract visual cool rating."

IT IS!

the desire to run serious power all day without seizing is EXACTLY why i'm here.

don't despair wari!

they don't see it, you'll have to explain the 2-stroke afr gauge i guess...

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see, now the information is becoming slightly useful...but still not that useful. expecially if what someone said about oil ruining afr gauges is correct.

northern mike, as well, you need to pipe down about your engineering degree. no ones debating building performance parts doesnt use engineering information/skills but give an engineer a theory and no information and no tools and he's still not going to be able to do anything with it. and you mention tuning using empirical knowledge...surely wari is suggesting we do exactly the opposite?!

wari, im sorry im not as someone said "hating", i think this could be useful if you explained it.

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crackstar, "The process of measurement is central to quantitative research because it provides the fundamental connection between empirical observation and mathematical expression of quantitative relationships"

I hope i'm reading that right and i hope you meant for that to be support to my statements. "The process of MEASUREMENT is central to..." You can only use that chart for "empirical observation" until you can actually MEASURE something. Not just ride the bike around and say "hmm this feels lean".

but then wari, _that's_ exactly what i was looking for. So you need all of those tools (or at least the afr guage), to use that chart? That alone makes it not worth it to me. Dont get me wrong, i can understand the desire to mathematically tune a bike. So i can totally see where youre coming from, and im not "hating" on anyone else. Wanting to _really_ tune your bike is a great thing. But even with those tools, i dont think that chart is even descript enough to make it worth using. Im not bashing it, or you. Its just that im not an advanced tuner, but i think i can get pretty close to nicely tuned without any of that information. I'd better hope so, at least, im going to have to in a few weeks!

And you should know better than i do not to trivialize the pursuits of most of the serious tuners on here. I think most people here acknowledge the fact that two strokes arent "magic" and do more than just buy parts for the cool stickers. Thats a generalization i like to reserve for tomos jersey boys. And youre right about performance tuning, this is where youre supposed to help others get the most out of their bikes. Thats what you're doing, and thats what those guys are doing when they write up reviews or "advertisements". I assume you've read some, but the fact that you exagerate to the point of saying theyre based on an abstract cool look factor kind of surprises me. I'd say theyre the exact opposite. Theyre the exact kind of scientific research i figured you'd support.

Well like i said im not bashing wari for coming up with this chart or anyone who wants to use it. Its not my place. Im just saying why it isnt as useful as it could be had it been more thoroughly explained.

And wari.. i hope this doesnt mean you wont still help me with my moby troubles? Like when i cant figure out how to put my chain back on?

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