661 Oil Test 32:1 vs 40:1 vs 50:1 ?

[Ron660]

Like 800 and h1r ?

When I went from stihl ultra 50:1 to 800 off-road at 32:1 in my 660 a significant adjustment was needed. I've noticed when ambient temps fluctuate 30 degrees or so a slight carb adjustment is needed. Less than that I just go with it as long as it's not 4-stroking under load.

 

[bwalker]

When I went from stihl ultra 50:1 to 800 off-road at 32:1 in my 660 a significant adjustment was needed. I've noticed when ambient temps fluctuate 30 degrees or so a slight carb adjustment is needed. Less than that I just go with it as long as it's not 4-stroking under load.

Certain saws are more sensitive than others as well. A ported ms260 is very sensitive IME to small changes in temp. While my older ported 372's run pretty good most all the time.

 

[bwalker]

When I went from stihl ultra 50:1 to 800 off-road at 32:1 in my 660 a significant adjustment was needed. I've noticed when ambient temps fluctuate 30 degrees or so a slight carb adjustment is needed. Less than that I just go with it as long as it's not 4-stroking under load.

One other thing. If an engine is four stroking it's literally choking on fuel. I have always adjusted the carb till it cleans up no load, then made some cuts and adjusted till it felt best. I then take a tach reading no load and you have a reliable point to tune to.

 

[Trx250r180]

When I went from stihl ultra 50:1 to 800 off-road at 32:1 in my 660 a significant adjustment was needed. I've noticed when ambient temps fluctuate 30 degrees or so a slight carb adjustment is needed. Less than that I just go with it as long as it's not 4-stroking under load.

I keep a screwdriver in my pocket whenever cutting because of that ,nothing more aggravating than a blubbering sounding saw to me ,other than one with a dull chain .

 

[KG441c]

When I went from stihl ultra 50:1 to 800 off-road at 32:1 in my 660 a significant adjustment was needed. I've noticed when ambient temps fluctuate 30 degrees or so a slight carb adjustment is needed. Less than that I just go with it as long as it's not 4-stroking under load.

Thats normal. When u r trying to force more oil through a opening adjusted for 50to1 an adjustment will be necessary but that has nothing to do with the oil but rather the amount

 

[Trx250r180]

Certain saws are more sensitive than others as well. A ported ms260 is very sensitive IME to small changes in temp. While my older ported 372's run pretty good most all the time.

Your 260 is ported now Ben ?

 

[Moparmyway]

I can tune my 066 by ear and it will 4 stroke out of the wood @ 15,000
It makes its most power tuned to 13,200. I know this because this is where it holds the most RPM while cutting.

Anyone wanna guess how bad its blubbering at 13,200 ?

 

[bwalker]

Your 260 is ported now Ben ?

I wasn't speaking of my current 260. I have had 260's ported by EHP, Greffard and Walkers

 

[KG441c]

I can tune my 066 by ear and it will 4 stroke out of the wood @ 15,000
It makes its most power tuned to 13,200. I know this because this is where it holds the most RPM while cutting.

Anyone wanna guess how bad its blubbering at 13,200 ?

Probably sounds like a nanny goat. Most saws will take more fuel to make more power but adjusting porting for higher rpm and more fuel flow can bring that rpm back up? My 241 was strato gutted and intake lowered and taking on all kinds of fuel but transfers and exhaust was raised also and maintained rpm in the cut

 

[Ron660]

I can tune my 066 by ear and it will 4 stroke out of the wood @ 15,000
It makes its most power tuned to 13,200. I know this because this is where it holds the most RPM while cutting.

Anyone wanna guess how bad its blubbering at 13,200 ?

13200 must be tuned for big wood.

 

[weedkilla]

why not just buy 2 different oils -

mix brand A - 50:1

mix brand B - 50:1

run a tank with A
run a tank with B

tell us what you think

Happily, anyone care to suggest an oil that runs the richest/needs the most leaning out on an adjustable carb?
That's all I'm asking. Throw the dog a bone without making him re do everything you've tried.

 

[Moparmyway]

13200 must be tuned for big wood.

36" and .404

 

[Trx250r180]

Happily, anyone care to suggest an oil that runs the richest/needs the most leaning out on an adjustable carb?
That's all I'm asking. Throw the dog a bone without making him re do everything you've tried.

More oil actually creates a lean condition

 

[KG441c]

36" and .404

Bet with that bar buried it doesnt 4 stroke with that kinda load

 

[KG441c]

More oil actually creates a lean condition

Yep. Higher concentration of oil trying to be forced through the same opening adjusted for 50to1 requires the orfice to be richened or opened more to flow the lower ratio of oil

 

[Trx250r180]

I can tune my 066 by ear and it will 4 stroke out of the wood @ 15,000
It makes its most power tuned to 13,200. I know this because this is where it holds the most RPM while cutting.

Anyone wanna guess how bad its blubbering at 13,200 ?

A real saw blubbers @ 15500 still loaded with a 36 and .404

 

[blsnelling]

Yep. Higher concentration of oil trying to be forced through the same opening adjusted for 50to1 requires the orfice to be richened or opened more to flow the lower ratio of oil

Are you saying it's because of a higher viscosity?

 

[Moparmyway]

A real saw blubbers @ 15500 still loaded with a 36 and .404

Video of you running it with white gloves .................. or it never happened

 

[KG441c]

Are you saying it's because of a higher viscosity?

Yes the way I see it Brad. If u have orfice at say .040 and adjusted to flow say 30 wt oil and switch to say 100wt oil the orfice wont flow the same without increasing it hence the lean condition goin to the higher viscosity

 

[blsnelling]

But it's not near that thick when thinned with gasoline. I would think the viscosity difference of pre-mix at various ratios would be nearly immeasurable. I could be wrong, but I can't see viscosity having anything to do with it. JUST MY OPINION. I believe it's because there's simply less fuel/volume.