Two-Stroke Oils: All the Same?

[Tomos770]

I agree, modern oils and fuels don’t seem to give the brown indication they use to!

For reference, the only thing different is the oil used here. Castor = brown, Synthetic = grey.

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I have the same colour pattern on my huskqvarna 450 X-torq.....just slightly grey bcs I was using Motul 800 in the past use....I just tought that maybe it is set too lean or it has evolved an air leak somewhere....

Same with a trimmer (old tech though....piston ported).....it is clearly 4stroking @WOT....but its spark plug looks like if it would run lean

What confuses me the most is absence of so called "fuel ring" on the sparkplug itself....

 

[Tomos770]

It came to the point.....that I have bought a blister of Stihl HP mineral oil.....so that I will see if sparkplugs will become "coffe brown" with use

 

[huskihl]

Also wanted to update you guys with Amsoil Saber 32:1. The first time I tested it I did 20 mins loaded by about 1000 rpm below max rpm - no longer 4 stroking, but I suppose, not really what an engine would see under use. I got a heap of carbon.

Are you sure that piston got cleaned off after using ultra? Or another oil? That doesn’t look like just a couple hours use and I’ve never seen saber leave a carbon pattern like that

 

[Vintage Engine Repairs]

Not sure where you read a couple of hours, It was 20 minutes each time. Yes I’m certain the piston was clean at the start of the test. Never used ultra in it, Amsoil was the only fuel used during the test.

It was actually two different strimmers I repaired this week, but for the ease of writing, I just wrote “cleaned the piston” The first image was the stihl strimmer, second was a pope. Stihl was ran loaded by 1000 rpm and left a dirty piston, pope by 3,000 rpm and it was light tan on the crown.

It’s also worth noting, the intake and exhaust in the stihl both go out the back of the engine. I presume that will drastically change swirl pattern?

Stihl cleaned before test:





Pope cleaned before second test

 

[OM617YOTA]

Do you have to retune an engine, if the only variable is changing the mix ratio.

How a string trimmer reacts isn't applicable to a chainsaw that four strokes out of the cut, and then doesn't.

Back with bean oil, when the oil mostly just got blown out the exhaust and not burned, yes a richer oil mix meant less fuel for the same carb settings. Modern(meaning the last 30 years) oils burn with the fuel, and contribute to the BTU content of the fuel. A richer oil mix means more fuel for the same carb settings.

 

[The Shooters Apprentice]

I’ll Have to try to grab a pic of the piston from one of my saws that I run saber in, but they are spotless clean.

 

[Vintage Engine Repairs]

How a string trimmer reacts isn't applicable to a chainsaw that four strokes out of the cut, and then doesn't.

It’s identical. A string trimmer should 4 stroke out of load then clean up under load…

 

[OM617YOTA]

It’s identical. A string trimmer should 4 stroke out of load then clean up under load…

You might have me there, that's not something I've seen before. Still not what you tested in the video, though.

 

[Vintage Engine Repairs]

You might have me there, that's not something I've seen before. Still not what you tested in the video, though.

Yep it was, if you see at the start it’s 8000 rpm with normal length line. I then say I’m going to load it up by putting extra line on. I put longer line on to load up the powerhead to replicate it running under a consistent load. It dropped it by 3,000 rpm. Then I started the testing.

 

[OM617YOTA]

I'll have to relisten for 4 stroking with normal line, then smoothing out after you add load.

 

[jellyroll]

I don't have a guard on my trimmer and with about 20 inches of line it is 4 stroking out of the grass but smooths out under load.
Even running crappy api tc or jaso fb oils the engine will stay clean internally.

 

[Vintage Engine Repairs]

I'll have to relisten for 4 stroking with normal line, then smoothing out after you add load.

I speed it up in the video, but here is the clip not sped up to hear 4 stroking.

View attachment IMG_8594.MOV

 

[North by Northwest]

Are you sure that piston got cleaned off after using ultra? Or another oil? That doesn’t look like just a couple hours use and I’ve never seen saber leave a carbon pattern like that

I don't known of anyone running Saber that rich , 40:1 is it usually & very clean !

 

[North by Northwest]

It’s identical. A string trimmer should 4 stroke out of load then clean up under load…

Same 2t engine principals , perhaps not the same high compression as within Commercial chainsaws although probably reasonably close . Most of the top 3 world class saw manufacturers also provide trimmers , brushcutters & blowers ! . I know brushing would simulate the loading of saw cutting , rather well lol.

 

[Vintage Engine Repairs]

Same 2t engine principals , perhaps not the same high compression as within Commercial chainsaws although probably reasonably close . Most of the top 3 world class saw manufacturer s also provide trimmers , brushcutters & blowers ! . I know brushing would simulate the loading of saw cutting , rather well lol.

Yeah very close if not the same 160-180 psi ised is typical on the ones I’ve tested.

 

[North by Northwest]

How a string trimmer reacts isn't applicable to a chainsaw that four strokes out of the cut, and then doesn't.

Back with bean oil, when the oil mostly just got blown out the exhaust and not burned, yes a richer oil mix meant less fuel for the same carb settings. Modern(meaning the last 30 years) oils burn with the fuel, and contribute to the BTU content of the fuel. A richer oil mix means more fuel for the same carb settings.

More oil = less fuel in the fuel mixture since its replaced by oil !

 

[North by Northwest]

Yeah very close if not the same 160-180 psi ised is typical on the ones I’ve tested.

That's spot on with stock homeowner class saws.

 

[Vintage Engine Repairs]

That's spot on with stock homeowner class saws !

These are used top ends at 160-180, not new

 

[sean donato]

Didn't you use new rings Tom? Typically you'll gain some compression once the ring beds in.

 

[North by Northwest]

These are used top ends at 160-180, not new

Then there is little wear , thats typical compressions readings , 160-165 # & 175-180 # . Sometimes higher on prograde or ported units . Are these cold readings ?