Fuel mix ratio and carb tuning

[jakethesnake]

I add more oil to my 55 and it runs out the muffler. Still runs great. I be confused too. I’ll just stick to what works fee me.

 

[angelo c]

I add more oil to my 55 and it runs out the muffler. Still runs great. I be confused too. I’ll just stick to what works fee me.

which brings to mind the "other" eternal question ?

How does the oil ratio effect the screws in on a Hoosky ? ( wheres that dern 'bangin muh head' emogii ?)

 

[Keith Gandy]

Yes, opening the H will ensure enough fuel gets in to keep
the engine running cool enough, and we all need to ensure this.
But in doing so there will still be more oil in the system, which is
fine as long as it does not interfear with the plug and spark screen
too much, and over time it will clog the rings.

My own feeling is, ensure you have enough oil in your mix,
ensure you up the H screw to keep your engine cool.
Tuning in my eyes will cool down a saw,
where adding oil will lubricate it.

As long as we know how one effects the other, then we can set up as
we see fit.

If one drops the oil ratio say from 50to1 to 32to1 and leaves the carb tuned for 50to1 the saw will be lean and starve for fuel. Retuning the h speed to richen is necessary

 

[huskihl]

If one drops the oil ratio say from 50to1 to 32to1 and leaves the carb tuned for 50to1 the saw will be lean and starve for fuel. Retuning the h speed to richen is necessary

I believe our friend @Moparmyway said it best.
Its what you learn, after you already know it all, that counts

 

[jakethesnake]

If one drops the oil ratio say from 50to1 to 32to1 and leaves the carb tuned for 50to1 the saw will be lean and starve for fuel. Retuning the h speed to richen is necessary

I see the point there just seems like in my real world experience it isn’t alwaus the case. Should be I guess but my 272 and 55 seem to not care or change tune much if any. My 346 will react to any change dramatically

 

[Keith Gandy]

I see the point there just seems like in my real world experience it isn’t alwaus the case. Should be I guess but my 272 and 55 seem to not care or change tune much if any. My 346 will react to any change dramatically

In that case u were way rich to start at 50to1. Most folks think adding more oil to the fuel makes the saw richer which isnt the case if it isnt retuned or it was already on the extreme rich side

 

[Keith Gandy]

If a saw is tuned spot on for 50to1 and and the orfice is letting just enough fuel through and tuned correctly and not on the rich side, adding more oil molecules to the fuel without tuning isnt gonna let the same amount of fuel through the orfice tuned for 50to1, hence the saw will run leaner

 

[Likesaws]

If a saw is tuned spot on for 50to1 and and the orfice is letting just enough fuel through and tuned correctly and not on the rich side, adding more oil molecules to the fuel without tuning isnt gonna let the same amount of fuel through the orfice tuned for 50to1, hence the saw will run leaner

So how much difference will it make from 50-1 to 40-1?
Some here have said no need to retune. I think a lot of people tend to tune rich anyway. My be because of that. How many of you retune for this?

 

[Al Smith]

Now then just a simple question .If those who advocate running mixtures such as 50 to 1 ratio explain how most chainsaw racers with 3 to 5000 dollar racing saws run much richer mixtures and why they do it .Are they wrong ?

 

[Likesaws]

Now then just a simple question .If those who advocate running mixtures such as 50 to 1 ratio explain how most chainsaw racers with 3 to 5000 dollar racing saws run much richer mixtures and why they do it .Are they wrong ?

No I think they are right. They have a very special made saw, that is what is needed for that saw to run right. The oil won’t burn saw up. Heat is what burns up saw. That comes from lean tune on saw not oil in mix.
People who don’t know to run saws scare me over rev saws and don’t load them correctly in the cut cause a lot of saw problems.

 

[Keith Gandy]

So how much difference will it make from 50-1 to 40-1?
Some here have said no need to retune. I think a lot of people tend to tune rich anyway. My be because of that. How many of you retune for this?

Im really not sure

 

[retro]

50:1 oil/fuel ratio is probably sufficient for most work saw motors while idling. At 14,000+ RPMs...? Not a chance! Racing saws require lots of extra oil for the same reason a stock saw needs more oil. Displacement vs RPMs. Oil migration and retention times suffer most in small motors being operated at very high RPMs. So whats so difficult about adding sufficient oil and tuning the carb for it..?

 

[Al Smith]

40-50-or 32 to one it's just a slight turn on the high speed jet .Heat of the day ,elevation figure into the mix but it's just a little screw driver and 2 seconds to rectify and it doesn't take a tachometer as some might suggest .

 

[Al Smith]

Speaking of tachometers .I get a kick out of Rich D of Oregon who has "shop talk" on some of his e-bay deals .Using a tach before he makes a demo cut on whatever he tries to sell .It's all for show and doesn't mean anything but eyewash .Tachs are nice to check something but anybody who knows anything relies on the good old ear --unless they are stone deaf ---

 

[Keith Gandy]

Awesome display kicking off Christmas celebration in Natchitoches, La. Riverbank

 

[Greenerpastures]

Now then just a simple question .If those who advocate running mixtures such as 50 to 1 ratio explain how most chainsaw racers with 3 to 5000 dollar racing saws run much richer mixtures and why they do it .Are they wrong ?

No they are not wrong, they are 100% right.
Lubrication reuirements rise in relation to load,
this is the way to go, but you do realize that to keep
friction down, larger clearances are left, and a racing engine
will only last a short time before having to be re built, its the same
in Formyla 1,
A lot more fuel also goes through these engines, for a reason.

Lubrication and fuelling are two competely different issues,
trouble is, in a two stroke chainsaw engine they are combined, so if you
alter one you have altered the other.
Fuel aoso lubricates to an extent, like diesel in an injector,
it has its limitations, and can never replace oil where the need
arises, but with two stroke chainsaws, lube and fuel are combined in one
process and in one medium.

 

[Greenerpastures]

Speaking of tachometers .I get a kick out of Rich D of Oregon who has "shop talk" on some of his e-bay deals .Using a tach before he makes a demo cut on whatever he tries to sell .It's all for show and doesn't mean anything but eyewash .Tachs are nice to check something but anybody who knows anything relies on the good old ear --unless they are stone deaf ---

Not completey true, I have a saw that when fourstroking has less than 400 rpm to go before it hits the limiter.
And the manufacturer gives a different limiter cut in threshold that
is much higher than the actual saws limiter,
so how would I have found this out without a tach.
But yes, a tach is no match for what is actually taking place in the cut,
you acn measure all you want in this regard and get no where.

 

[retro]

I use a tachometer during every carb retune so I can be both accurate AND consistent. I don't leave for the woods without it.

 

[Greenerpastures]

I am happy to have used a tach for initial diagnosis,
but after that, I can manage, its freat for finding where
the limits are, and as said for consistency, and even repeatability,
but as I have no two saws the same, repeatability is not an issue.

 

[bwalker]

If one drops the oil ratio say from 50to1 to 32to1 and leaves the carb tuned for 50to1 the saw will be lean and starve for fuel. Retuning the h speed to richen is necessary

In all reality this rarely happens because most saws are set on the rich side and the change is very, very slight. The effect of a twenty degree swing in temperature has more impact than a miniscule change in oil ratio.