What oil is best? and what ratio?

[RI Chevy]

Lol. Thanks. I am glad I am not the only 1. [emoji106]
I should have clarified that I do tune regularly if needed. I tend to tune a tad on the rich side by choice.

 

[00wyk]

Even ported saws have low compression ratios. 92 octane is more than enough.

The fuel mixture is also far less stagnant than it is in most four strokes, even vortec engines and the like, which also allows lower octane. Some saws even have more swirl designed in to the cylinder than the typical two stroke design already naturally allows, like on modern Echo's. The more busy that mixture is before it combusts, the better it mixes and, well, combusts. I didn't notice obvious detonation on my saws until I went above 220 psi or just added way too much timing advance, but that is admittedly a small sample of maybe 4 saws. Having said that, bear in mind how much oil you put in to the mix also affects the octane rating overall. Ethanol also modifies your octane rating.

 

[Hedgerow]

Brown...






It's the new blue..

 

[Hedgerow]

Hooray cheap oil!!!!

 

[bwalker]

The fuel mixture is also far less stagnant than it is in most four strokes, even vortec engines and the like, which also allows lower octane. Some saws even have more swirl designed in to the cylinder than the typical two stroke design already naturally allows, like on modern Echo's. The more busy that mixture is before it combusts, the better it mixes and, well, combusts. I didn't notice obvious detonation on my saws until I went above 220 psi or just added way too much timing advance, but that is admittedly a small sample of maybe 4 saws. Having said that, bear in mind how much oil you put in to the mix also affects the octane rating overall. Ethanol also modifies your octane rating.

Cranking pressure is pretty meaningless. The calculated compression ratios of even the wildest saws is pretty low.
Unless you have a detonation counter its hard to know if your actually detonating unless its pretty severe. I am a believer that most seizures are causes by detonation that is set in motion by a lean mixture.
Also keep in mind that the combustion chambers of saws are very crude and really limit swirling. The squish clearance in and of itself on many would render even a properly designed chambers ineffective.

 

[huskihl]

View attachment 147970

Hooray cheap oil!!!!

The case of Dolmar oil on eBay when I bought it worked out to $1.75 per 13oz bottle. I's pretty happy with that.

 

[Hedgerow]

The case of Dolmar oil on eBay when I bought it worked out to $1.75 per 13oz bottle. I's pretty happy with that.

You got a buy on that *s-word..

 

[Willard]

Very true and if it's a Stihl in my 066 case
Can't beat the effective thermal and vibration isolation rubber intake manifolds on the Stihls since the 042 came out with it in 1976 same year the 162SE was introduced.
I have run Jonsereds and 2 series Huskies since 1974 and I always had to carry a carb screwdriver in my pocket to reset the carb from vibration every few days when 8 hr a day logging.
Got my first Stihl in 1980 and only needed to re set the carb during season temperature changes.
That right there says alot.

Going to edit some Stihl info I crossed wires on here.
1976 Stihl 042AV introduced with first Master control switch, first in its class with a front mounted muffler with thermal and vibration isolated module fuel tank with carburetor mounted in air box . This design went on into the 028, 038, 048, 024,034,064,084 etc. of the future.

The Stihl 030AV introduced in 1970 was the first with a rubber intake manifold boot.

 

[huskihl]

You got a buy on that *s-word..

I just bought another case for a customer. $2 per 13oz bottle. You could mix all kinds of other oil in with it and it would still be blue. The stuff has a boatload if dye in it

 

[RI Chevy]

The Dolly oil?

 

[huskihl]

The Dolly oil?

Yes

 

[RI Chevy]

It is very, very, very blue. But I like it.

 

[lehman live edge slab]

Going to edit some Stihl info I crossed wires on here.
1976 Stihl 042AV introduced with first Master control switch, first in its class with a front mounted muffler with thermal and vibration isolated module fuel tank with carburetor mounted in air box . This design went on into the 028, 038, 048, 024,034,064,084 etc. of the future.

The Stihl 030AV introduced in 1970 was the first with a rubber intake manifold boot.

I have an 030, the fast idle for a cold start is a big button on top of the back handle. I’m wondering if it’s all original or not though, I’ve seen pictures with a side fill tank but mine is top fill like an 031. Maybe somebody switched to an 031 tank.

 

[lehman live edge slab]

View attachment 147970

Hooray cheap oil!!!!

Looks like the cheap oil is jasco fd rated, I’d run it

 

[00wyk]

Cranking pressure is pretty meaningless. The calculated compression ratios of even the wildest saws is pretty low.
Unless you have a detonation counter its hard to know if your actually detonating unless its pretty severe. I am a believer that most seizures are causes by detonation that is set in motion by a lean mixture.
Also keep in mind that the combustion chambers of saws are very crude and really limit swirling. The squish clearance in and of itself on many would render even a properly designed chambers ineffective.

I doubt any of us will need a detonation detector to figure out this picture.

The swirling on a 2 stroke starts long before the mix reaches the chamber. Unlike most petrol engines that folks try to describe of as being a pump, a 2 stroke engine actually IS a pump. It pumps the mixture around the case, through the transfers, and then in to the combustion chamber, and this after sucking it in through the intake. No other petrol engine swirls the mixture remotely as much before combustion. A chainsaw is basically supercharged by design.

 

[huskihl]

I doubt any of us will need a detonation detector to figure out this picture.

The swirling on a 2 stroke starts long before the mix reaches the chamber. Unlike most petrol engines that folks try to describe of as being a pump, a 2 stroke engine actually IS a pump. It pumps the mixture around the case, through the transfers, and then in to the combustion chamber, and this after sucking it in through the intake. No other petrol engine swirls the mixture remotely as much before combustion. A chainsaw is basically supercharged by design.

...if popping (or 4 stroking) out of the cut is in fact detonating

 

[RI Chevy]

Timing advanced too much?

 

[00wyk]

Timing advanced too much?

Way too much. Nearly half the keyway. It was a pretty cool day, so it took a while to warm up. But once that thing did, it detonated readily. Pulled it back to 33% or so, and it was fine. Compression on that saw was..uh...lemme find it here... 195psi. But that gauge was always about 8-10 psi on the high side as it has no hose.

 

[huskihl]

Timing advanced too much?

Idk. Never heard it cut

 

[junkman]

Brown...






It's the new blue..

shame on you