Stihl 044 tech info

[Butterbean 150]

Found this in the Stihl 044 repair manual. They are recommending "25-1 with all other branded two-stroke,air cooled engine oils"
Anyone else catch this in the manuals? Might be a reason so many top ends are getting toasted.

 

[Chainsaw Jim]

The 044 was made well before all the EPA 50:1 bullchit.

 

[Butterbean 150]

I think im gonna run 4oz oil mix to the gallon. Makes figuring out how much oil to mix easier. Been using Poulan Pro from Sally World but I got a gallon of Amsoil Saber I'll be using.

 

[SteveSr]

Found this in the Stihl 044 repair manual. They are recommending "25-1 with all other branded two-stroke,air cooled engine oils"
Anyone else catch this in the manuals? Might be a reason so many top ends are getting toasted.

Oils have gotten MUCH better in the decades since this was published. You should be fine using today's *quality* oil at 40:1 or 50:1 as recommended by the oil manufacturer. Watch out for TOO MUCH oil with limited carbs. This can cause an over lean condition followed by piston seizure. The extra oil displaces the gas.

 

[Butterbean 150]

Oils have gotten MUCH better in the decades since this was published. You should be fine using today's *quality* oil at 40:1 or 50:1 as recommended by the oil manufacturer. Watch out for TOO MUCH oil with limited carbs. This can cause an over lean condition followed by piston seizure. The extra oil displaces the gas.

I dont understand the lean condition you speak of. If i tune the carb low/idle and high side to spec, then isnt the same amount of gasoline being burned in the cylinder? I could understand your point if during initial carb setting I could not get it to richen up, but thats not the case. It tuned just fine when i mixed the oil I have at 25-1 ratio using 93 octane non-ethanol gasoline. There was no tuning issues during setup. The 044 smoked a lil more with this mix than 50-1. Other than that, there were no issues. I do not have a laser temp gun to check cylinder temps with though. If im missing something here, chime in.

 

[Spring1898]

That is correct.

For those not in the know.
The oil in the mix is not completely burned, as it has to lubricate the cylinder.
So when you increase the amount of oil in a mix you have a proportionately smaller amount of gas in the same volume.

Since the carburetor flows the same volume (it does not distinguish between gas vs oil amount), the net amount of gasoline flowing into the engine is less with a 25:1 than a 50:1.
Less gas to burn = leaner burn = bad

Solution = "Richen" the carburetor to allow a larger total volume gas/oil to enter the cylinder to achieve the correct amount of combustible gasoline per combustion cycle.
Then watch the smoke pour out as the amount of oil entering the cylinder also increases...

 

[SteveSr]

I dont understand the lean condition you speak of. If i tune the carb low/idle and high side to spec, then isnt the same amount of gasoline being burned in the cylinder? I could understand your point if during initial carb setting I could not get it to richen up, but thats not the case. It tuned just fine when i mixed the oil I have at 25-1 ratio using 93 octane non-ethanol gasoline. There was no tuning issues during setup. The 044 smoked a lil more with this mix than 50-1. Other than that, there were no issues. I do not have a laser temp gun to check cylinder temps with though. If im missing something here, chime in.

As long as there are no limiter caps on the carb you should be able to tune it for any oil ratio that you want. The issue is that the presence of limiter caps will prevent you from going rich enough with a high oil ratio like 25:1. Think of it this way... the carb sets the ratio of Air : (Fuel + Oil). So by adding oil the amount of fuel goes down causing a lean condition unless the carb is adjusted to compensate for more oil.

 

[Spring1898]

That said if you have Saber or Poulan Pro Synthetic, those are pretty good quality oils anecdotally here on the forums and from some builders and probably don't require the 25:1.

 

[Butterbean 150]

That makes sense about the carb needing to be richened up. Ill buy that for a dollar. Thanks for the input guys. I remived the limiter nibs on the needle caps and put them back on. My 044 did have a little more smoke, but that don't bother me. I would rather lnow yhe bearings are getting the lube they need. I pulled the spark screen years ago anyway. Do you guys think that is too much oil for the 044 at 25-1? I usually mix my regular mix at 3 oz to the gallon, comes out at something like 42-1 ratio. Would there be a reason not to run it at 25-1 like the manual recommends?

 

[Spring1898]

I usually run 40:1 just for my sanity, but there are many who simply run a quality oil at 50:1, which is what they are designed for.
Remember, the Stihl manual has their own oil as 50:1, that was probably an older white bottle formulation. There has been much improvement since then.
the 25:1 was simply for lesser quality oils.

The risk is accumulation of unburnt oil that clogs the muffler screen and can leak out from the saw and make a mess. Eventually it could turn back to tar/crude and gum things up.
More is not better.

 

[ericm979]

Excess oil can also cause more carbon to form. On a highly tuned race motorcycle that's making .36 hp/cc (a 45 hp 125 or 90hp 250 twin) it makes sense to run 25:1. But a saw is more like .08 hp/cc (a 6hp 77cc saw). That's a lot less stress. So you need less oil. Also the highly tuned race bike gets torn down often so carbon accumulation is not an issue. A work saw gets torn down when it's worn enough to need a rebuild.

Good explanation on how the carb meters fuel+oil and oil is not fuel.

 

[president]

That makes sense about the carb needing to be richened up. Ill buy that for a dollar. Thanks for the input guys. I remived the limiter nibs on the needle caps and put them back on. My 044 did have a little more smoke, but that don't bother me. I would rather lnow yhe bearings are getting the lube they need. I pulled the spark screen years ago anyway. Do you guys think that is too much oil for the 044 at 25-1? I usually mix my regular mix at 3 oz to the gallon, comes out at something like 42-1 ratio. Would there be a reason not to run it at 25-1 like the manual recommends?

The manual states,50 to 1 stihl brand 25 to 1 all others.That is their default not knowing the
oil quality of crappy oils you may dump in the mix.Stick to 40 to 1 caps removed and fattened
up (H) screw

 

[HarleyT]

An oil thread!!!!!!!!

 

[wyk]

That is correct.

For those not in the know.
The oil in the mix is not completely burned, as it has to lubricate the cylinder.
So when you increase the amount of oil in a mix you have a proportionately smaller amount of gas in the same volume.

Since the carburetor flows the same volume (it does not distinguish between gas vs oil amount), the net amount of gasoline flowing into the engine is less with a 25:1 than a 50:1.
Less gas to burn = leaner burn = bad

Solution = "Richen" the carburetor to allow a larger total volume gas/oil to enter the cylinder to achieve the correct amount of combustible gasoline per combustion cycle.
Then watch the smoke pour out as the amount of oil entering the cylinder also increases...

It's only bad if the engine is over heating from a lean run. After all - it is getting more lubrication, so less likely to seize as long as the heat is under control.
When I was younger, and worked in forestry and logging often enough, I rarely saw seized saws running 25 or 33:1. But I sure as hell see plenty of seized saws nowadays.

Many manuals well in to the early 2000's stated using 25 or 33:1 ratios for non OEM oils, well after the EPA started to crack down on saw emissions.
I have a 390XP manual that has such a statement in it.