Pre-Mix ratios

[Big Kahuna]

yes, rich oil mixture displaces the fuel, so you run leaner on the air fuel mixture.

 

[Odd Duck]

the difference in burning oil and burning gas is SIMPLE.

gas is explosive, it MAKES the combustion.

the OIL, being in there, is somewhat consumed ( generally not all of it, but some)

but it does not ADD to the combustion, in fact I contend that it is actually parasitic to the combustion process ( all lubing and ring seal properties aside)

Odd Duck, it sounds as if your mechanic agrees with my initial thoughts of rich premix leaning out the carb mixture.

Yep, he does.

Mark was telling me that while oil getting in the chamber of a 4 stroke will often lead to detonation, it generally doesn't with a 2 stroke unless you are really lean. That being said, at the same time, the extra oil is protecting the rest of the engine from the effects of detonation.

He was also quite certain that the more oil in the mix, the more power you get from the motor, and apparently not just because of increased ring seal and lubrication. He said he really hasn't gotten into the details of the exact chemical/physical nature of the reaction, he's researched it more from the lubrication/protection stand point. He just happens to have run across more than one article about oil:fuel ratios, comparisons with various mixes and power produced, major factors that affect the power, etc.

I wish he would haunt the boards more, he's a font of information on motors of all sorts. He doesn't like to get dragged into debates about stuff, he just quietly researches, soaks up information like a sponge, does his own testing and tuning and decides for himself if he agrees, or not, with prevailing theories.

I just know he keeps my toys and his toys in tip top shape/tune and many of our friends, as well.

 

[sjetrider]

the difference in burning oil and burning gas is SIMPLE.

gas is explosive, it MAKES the combustion.

the OIL, being in there, is somewhat consumed ( generally not all of it, but some)

but it does not ADD to the combustion, in fact I contend that it is actually parasitic to the combustion process ( all lubing and ring seal properties aside)

Odd Duck, it sounds as if your mechanic agrees with my initial thoughts of rich premix leaning out the carb mixture.

THE MAN MAY NOT BE VERY PRECISE IN HIS OIL MIXTURE, BUT HE KNOWS THE FUNCTION OF THE OIT FO SHO! LOL!!!!! :fing02:

 

[wydopen]

yamalube 40:1

 

[SJ Thumpa]

Kawi 550: 36:1 From memory recommended in the manual.

701 high comp race gas 40:1.

Lamey PV. Intend to go 32:1 as recommended. Intend to use either quicksilver as someone said above or if using Klotz, Klotz rep recommended Klotz KL307 ski craft for PV's.
For the Lamey PV I was told 32:1 because "rings will actually make more compression (less blow-by) and internals will last longer."

 

[Mouthfulloflake]

that is interesting Odd Duck,

I have read here or pwcyesterdecade where a guy ran the amsoil stuff 100:1 and said he could feel the difference in power ( since there was more fuel available to burn)

Ill do some reading on that too, there is a likely a 'sweet spot' where all the properties come together and the process is the best compromise between heat, and lube, and seal, and available fuel to combust.

interesting thinking.

speaking of chainsaws, I run mine 50:1 on 927, and use generic canola oil for the bar and chain!

 

[Odd Duck]

Remember, it is important in the testing that was reported, that they were very careful to keep the air:fuel mixture consistent. They did this by adjusting jetting or whatever else they needed to do. Apparently they were quite precise about it in the 2 particular articles he trusted (probably why he trusted them).

He also mentioned that the jetting is likely so rich in most people's skis, that they would likely not notice much difference with higher amounts of oil in the fuel.

I don't know if he saved copies of those articles or remembers where he found them, but I'll see if I can get him to post them if he can.

 

[Big Kahuna]

That was the pure synthetic.......... I use to run that but ran it at 50:1, could not bring myself to run 100:1

 

[Ericfox]

Anyone out there using amsoil dominator on a modified 701? I'd be curious how your ratio compares with the above numbers... I ran it 40:1 on my blaster, but I bet I could have run it at 50:1 or higher.... I may try it at 50:1 on my superjet this year...

 

[crammit442]

Remember, it is important in the testing that was reported, that they were very careful to keep the air:fuel mixture consistent. They did this by adjusting jetting or whatever else they needed to do. Apparently they were quite precise about it in the 2 particular articles he trusted (probably why he trusted them).

He also mentioned that the jetting is likely so rich in most people's skis, that they would likely not notice much difference with higher amounts of oil in the fuel.

I don't know if he saved copies of those articles or remembers where he found them, but I'll see if I can get him to post them if he can.

I agree with his thoughts. If a change from 50:1 to 40:1 or even 32:1 made a boat run noticeably different, I would say that you either have VERY finicky carbs or were tuned on the edge of lean anyway. I run 32:1 castor in all my stuff and the only other oils I would really even consider are R-50, K-2, or Amsoil Dominator. I've read all those articles and have all the books too and it sounds like I've come to the same basic conclusions as your husband. He sounds like a smart guy!:burnout:

 

[Odd Duck]

I keep telling everybody he's a genius mechanic and people think I say that just cuz I love him. But he really is a genius mechanic. :biggrin:

And he runs 32:1 in case anyone was wondering.

 

[bad93blaster]

the oil doesnt burn. it feeds the crank or gets spit out the exhaust.

so the cylinder get no lube at all?

im glad there is some smart people in here

 

[Wolf Child]

so the cylinder get no lube at all?

im glad there is some smart people in here

you are knit picking. if the oil gets to the crank, you dont think it gets to the cylinder?

hmmm....:sneaky:

 

[ger87410]

Generalizations and assumptions for knowledge of the obvious be damned!!!

 

[Mouthfulloflake]

I have an old weedeater that the shaft is broken on.

I wish I had some way to measure its power, Id do some tests starting at 16:1 and ending at 100:1 just to see.

I really dont understand how 32:1 can make more power than 50:1.

there is more LUBE, for less friction, and better ring seal, but there is also LESS fuel to burn and push the crank around?

can someone explain this to me?

IM not trying to argue at all, just trying to get my head around the concept.

 

[750SX]

I believe Alexander Graham Bell achieved the most power at 20:1. (I'm not 100 percent sure on this, but I know he was using a ton of oil.) Why he reached the most power at this mixture, I do not know.

 

[Shonuff]

I'm running Dominator at 60:1.

Do I go oil richer?

 

[Ericfox]

I'm running Dominator at 60:1.

Do I go oil richer?

I cant remember what ski, engine, and mods you have.... if you run 60:1 dominator with no issues in a similar setup as mine-->that would definately give me good feelings of running 50:1 or maybe even 60:1 in mine... what do you have?

 

[750SX]

I use dominator at 40:1 in everything I own.

 

[32vickie]

with all this said, I would assume that if you had a lawn boy mower ratio 32:1, echo trimmer at 50:1 and chain saws at 32:1 or 16:1 for an older one. you should be able to use a good oil at 40:1 without seeing much difference. Klotz ski craft or R50?

Doug