What oil is best? and what ratio?

[RalphK]

There was an article written in a dirt bike magazine years ago titled less is more or more is less. The conclusion from testing was, if memory serves, ratios down to about 16/18:1 produced the most power and least amount of wear.

 

[davidwyby]

There was an article written in a dirt bike magazine years ago titled less is more or more is less. The conclusion from testing was, if memory serves, ratios down to about 16/18:1 produced the most power and least amount of wear.

I have heard same...but how about heat?

Generally more heat is a byproduct of more power.

(hot climate here)

 

[RalphK]

Can't remember what the article said about CHT's, more power means more heat, can't beat physics. I also don't remember what power increases were mentioned on the different ratios, but I would imagine it wasn't huge.

 

[Egg Shooter]

http://www.off-road.com/dirtbike/tech/twostroke-fuel-ratios-premix-myth-vs-reality-54169.html

 

[Egg Shooter]

http://www.bridgestonemotorcycle.com/documents/oilpremix6.pdf

 

[ammoaddict]

http://www.off-road.com/dirtbike/tech/twostroke-fuel-ratios-premix-myth-vs-reality-54169.html

Interesting

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[Egg Shooter]

https://motocrosshideout.com/2-stroke-dirt-bike-pre-mix-101/

 

[Egg Shooter]

The one above is long but worth the read. Newer dyno tests at the end.

 

[Sawrain]

Been thinking on this...it is said too much oil displaces gas and makes a saw lean. Or maybe it just burns hotter? Or maybe it restricts the jet too much?

Facebook = bad.

Saw carbs have screws

Facebook = bad, exactly what I thought to myself, but you beat me to it.

 

[jakethesnake]

I’m honestly still super confused by this.

 

[jakethesnake]

I run 32:1. It works for me. I’m thinking it’s more oil for the bottom end. Any way you think about it. Is it making me run leaner after tuning. I’d hope not. Wouldn’t think so. Wouldn’t see how. I’ve argued about this. I’m not an engineer. *s-word I’m not even good at working on carburetors. 32:1 hadn’t hurt anything. No piston scuffing. They’ve been run on everything between 50:1 3o ish to 1. Nothing failed yet.

^ lies. I blew my ported 346. The crank rod bearing went. Made me believe more oil in the tank would lead to more oil on crank bearings before the mix hit the cylinder.

Am I wrong or no?


Don’t the screws allow me to open more mix into the whole machine ?

im fuggin lost on this one. Someone smarter than me knows.

 

[jakethesnake]

I grasp if you don’t touch the screws at all.

but if you tune the saw to adjust. So.... then what happens. If I add more oil am I still lean??

this is where I get really lost.

I would think. This is bad when I think


Let’s say we went 10:1. Maybe you wouldn’t have enough adjustment on the carb. Then you would see a lean condition.

however my thoughts. Again this brain and lightbulbs going off isn’t likely going to figure lots of things out.

if I can tune the saw to where I know that bish is running rich. Due to performance.

40:1 isn’t more better for my bottom end than say 50:1?????

after I tune said bish. Is it then not running lean not rich but just kinda about right.

Ive bickered bout this before. Cause I think too much.

I guess I’m thinking use the oil amount you like 50:1 Is enough for most stock saws. I like more. But then tune for it and the extra I like is just for bearing lubrication.

am I wrong or nobody knows?

 

[rogue60]

I have heard same...but how about heat?

Generally more heat is a byproduct of more power.

(hot climate here)

Heat is a tune issue a lean tune=hot a fat tune=cold you want it in the middle as such that will also be the designed constant operating temperature of a saw for best everything combustion/cooling etc etc..
More oil doesn't make a 2T run hotter that's a tuning issue chainsaw carbs can handle and tune fine for a wide variation of mix ratios.
If a saw is pushed and worked to the max and in heat more oil and tuned for it will help keep that engine alive and running cooler simply because there will be more oil between moving parts preventing metal to metal contact and an added plus of better ring seal for more power win win..
I personally wouldn't recommend pushing a saw to it's limits and in heat running 50:1 no matter how good the oil supposedly is.

 

[RI Chevy]

Keep doing what your doing Jake. Go by your own results. The bearing in the 346 may have been bad or going bad. 32:1 and tune accordingly if your getting good results.

 

[Bull Mountains]

I run 32:1. It works for me. I’m thinking it’s more oil for the bottom end. Any way you think about it. Is it making me run leaner after tuning. I’d hope not. Wouldn’t think so. Wouldn’t see how. I’ve argued about this. I’m not an engineer. *s-word I’m not even good at working on carburetors. 32:1 hadn’t hurt anything. No piston scuffing. They’ve been run on everything between 50:1 3o ish to 1. Nothing failed yet.

^ lies. I blew my ported 346. The crank rod bearing went. Made me believe more oil in the tank would lead to more oil on crank bearings before the mix hit the cylinder.

Am I wrong or no?


Don’t the screws allow me to open more mix into the whole machine ?

im fuggin lost on this one. Someone smarter than me knows.

32:1 isn't making you running leaner provided your carb tuning is set properly.
I would also point out the difference in screw position from 32:1 to 50:1 is extremely small. Carb screws are just not that precise. Like small to the point you wouldn't see a difference in EGT if your engine was equipped with one. I know this because I actually tested it on a snowmobile with a EGT, CHT and a data logger.

 

[Bull Mountains]

Saw has to run hotter in my opinion to burn more oil ,I have had problems with pistons scuffing with more oil on my saws ,have been at 50 to 1 for several years now and piston is always wet with oil ,even milling, am sure if drilled jets out could tune it for more oil ,but fixed jets have their tuning limits with the 2 screws on the carb.my opinion like I said from saws I run over the years and what works for me.

A piston has never been scuffed by too much oil. They are scuffed by running lean.

 

[jakethesnake]

32:1 isn't making you running leaner provided your carb tuning is set properly.
I would also point out the difference in screw position from 32:1 to 50:1 is extremely small. Carb screws are just not that precise. Like small to the point you wouldn't see a difference in EGT if your engine was equipped with one. I know this because I actually tested it on a snowmobile with a EGT, CHT and a data logger.

Agree to all these points. This is what confuses me about more oil equals lean.

 

[ammoaddict]

Agree to all these points. This is what confuses me about more oil equals lean.

Rich or lean is referring to the fuel/air ratio. Nothing to do with the oil. If you add more oil you are taking up the space that would have been gas, so therefore you have less gas and the same amount of air, so therefore it creates a leaner fuel/air ratio. Make sense?

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[Sawrain]

Rich or lean is referring to the fuel/air ratio. Nothing to do with the oil. If you add more oil you are taking up the space that would have been gas, so therefore you have less gas and the same amount of air, so therefore it creates a leaner fuel/air ratio. Make sense?

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But it is to do with the oil when people are talking only about oil, right or wrong, people use the term rich or lean to describe their oil ratio, rich being more oil and lean less, the rich/lean tune while a factor of this, is not the main point of discussion.

Don’t know why everyone keeps ignoring any context of the statement, example below.

“richer oil mix”

Ok, I know I could test this, but I imagine it has already been done. Does a richer oil mix run hotter, assuming saw is tuned for it, etc.?

Yes it is true, a richer, say 40:1 vs 50:1 oil mix may result In a leaner tune as there is fractionally less fuel and the mix is fractionally more viscous.

Does it run hotter?

I would hope anyone who likes to discuss oil ratios keeps there saws tuned at all times, altitudes, temperature, fuel types etc, so I don’t get all the Facebook tears over lean running saws when at 40:1.

Just do what the manufacture sais bro, ok, I’ll run my 064 at 40:1.

My question is this, do they think a well
Tuned saw running 50:1 is less or more protected on 40:1 with no tuning change.

 

[sawmikaze]

Anyone remember when Julian said his 661 cut faster on a 50:1 ratio over 32:1....

Then he proved it with a video...