50:1 or 32:1 mixture

[MS-310]

One thing also,

It's not the best oils or how much oil you use its really how the Engine is produced. As of the type of steal the type or bearings and alot to do with RPM just some food for thought, (i like 38.5 to 1 ratio )

 

[blis]

Tell that to the thousands of moto-x, road race, snowmobile, outboard, and Kart racers to name just a few.
Kart racers frequantly run 16:1!
My Ski Doo snowmobile came from the factory set at 20:1 and I have ran it that way since new. Havent had any issues with running that way, which is more than I can say for some others running the same model who had their dealers adjust their oil pumps to the factory specified 40:1 setting. I would rather have a little insurance.

might be the thing that karts alot higher hp/cc ratio than saw and they also rev few k higher than saws... BUT more oil -> less power... also, racing world is different than chainsaw world...

btw,my 125cc italian motorcycle (35hp/14 000rpms) pumps 3% mix at max revs...

 

[bwalker]

BUT more oil -> less power...

Since the 70's it has been well known and documented(SAE papers on the subject) that the mor oil present in the mix the mor epower a two cycle engine makes. mac actullay authored a paper on thsi in the 70's.

 

[blis]

Since the 70's it has been well known and documented(SAE papers on the subject) that the mor oil present in the mix the mor epower a two cycle engine makes. mac actullay authored a paper on thsi in the 70's.

care to link any proof?

 

[Lakeside53]

Interestingly , in the last two tech session I attended with Stihl they were adamant that, with everything else being even, oil ratios of more less 50:1 (like 32:1) will reduce the life of the saw. I really pressed them on whether this was just the party line for EPA and the answer was no... the carbon that eventually builds up behind and around the rings is the issue. By "life" they are talking about hours in the 1000's.. Believe it or not.. it's just a data point. I asked them if a fatter mix gave a bigger buffer for extreme conditions, and they said "maybe", but that it depended on what got you first.


None of this means squat unless the type of oil used taken into account, so I just use the best oil and gas I can get. Right now the oil is a full synthetic.

I run 50:1 but with a slightly richer mixture setting than "max", but that's just me.

I certainly fatten up my mixes for milling, and richen the mixture, but that's not typical saw use, and I'm sure not going to get 2000 hours out of my mill saws!

 

[bwalker]

care to link any proof?

Go to www.SAE.org and do a search.

Interestingly , in the last two tech session I attended with Stihl they were adamant that, with everything else being even, oil ratios of more less 50:1 (like 32:1) will reduce the life of the saw. I really pressed them on whether this was just the party line for EPA and the answer was no... the carbon that eventually builds up behind and around the rings is the issue.

In most of the cases I have seen motors ran with more oil in the mix tend to be cleaner. Carbon may be a issue with Stihls crappy orange bottle oil, but not with a modern synthetic or semi synthetic.
Also consider the fact that much of the deposits you see in a two cyle come from the fuel. When running more oil in the mix you have more detergants to take care of these deposits before they form.
Here is a pic of a sled motor with more than a few thousand miles on it at 32:1. Pretty clean, eh?

 

[amdburner]

Hmmmm... more oil, more power..... I had a Kawasaki KDX175 that would not run well at all if the mix was even remotely off. Put in a little too much oil and it ran like crap. Cut the oil back and it would run like a banshee. My old Skidoo free airs had the same problem. Too much oil and you spend more time working on the sled than riding it. I found alot of my troubles went away when running at 50:1. The only engine I had that had any issue with it was a 399 in a Skidoo Nordik which the original rings wore but it had quite a few miles on it already before I owned it. I still have a 440 F/A and a 340RV F/A which run well. So, I guess I subscribe to belief that more oil is not always better. More oil leans the fuel/air mixture and changing carb settings will richen the fuel mixture but you are then also introducing more oil in a straight mix situation. Just adding my .02 since I took the time to read this whole thread.

 

[amdburner]

BWalker,
That is a pretty clean piston and exhaust port. What sled iis that from? Also, a take it that you removed the oil injection and are running straight mix? If you don't mind me asking why would you do this? Just curious.

Dave

 

[bwalker]

It is off a 800 polaris. I didnt remove the oil injection, I just cranked it up.
Its likely that your tuning problems back in the day had to do with the crappy oils back then and from improper carb tuning.

 

[Lakeside53]

In most of the cases I have seen motors ran with more oil in the mix tend to be cleaner. Carbon may be a issue with Stihls crappy orange bottle oil, but not with a modern synthetic or semi synthetic.
Also consider the fact that much of the deposits you see in a two cyle come from the fuel. When running more oil in the mix you have more detergants to take care of these deposits before they form.

I'll buy that. I asked them why not tell everyone to run on full syn and the answer was simply that people will buy the cheapest oil sold, and to be competitive, just like their competition, they still sell the dino oil.

At our store we're phasing out the old orange and mainly stocking the semi-synthetic "Super" blend. It's about 30% more expensive, but I'm not seeing any great price resistance at that level.

 

[amdburner]

BWalker,
Then you are running 32:1 at WOT. The injection system, if I am correct, runs anywhere from 150:1 at idle and up to 50:1 (at recommended setting). This is what I have read anyway.

 

[Lakeside53]

Here's some oil test done by Stihl. Don't draw excessive conclusion or applicability to saws from these. They are the results obtained by running BR600 4 mix blowers for 500 hours straight at full power. Saws get to thermally cycle which keeps some of the build-up down.

The Stihl "Ultra" is a full synthetic oil. The "Super" is "Semi-synthetic" (blend); the HP is the old dino "orange" and the Low smoke is now a discontinued mix oil.

The mix ratio is 50:1

 

[blis]

from those pics you can clearly tell that hp ultra did best job (not much carbon on top, skirt is clean)...

 

[amdburner]

Here is a link with an interesting oil test with large R/C aircraft engines. This is a 42cc engine.

http://www.geistware.com/rcmodeling/articles/oil_test/index.htm

 

[amdburner]

Lakeside53,
Thanks for the pics. Very informative.

Dave

 

[Canyon Angler]

Also, a take it that you removed the oil injection and are running straight mix? If you don't mind me asking why would you do this? Just curious.

Dave, I don't know anything about sled motors but I've seen several outboard motors with oil injection seize from the oil injector system quitting. I now run my 2-stroke outboards on 100:1 premix (in addition to the oil injection) in case that happens. It can be a long walk home from 50 nm offshore...

 

[amdburner]

Angler,
I have never had an injection system problem with my snowmobiles that wasn't caused by something I did wrong. A story that I would rather not tell. :bang: Anyway, outboard engines can be a different story from my experience. Some of the injection systems I have seen on them are questionable. Another problem I have encountered was with an Evinrude (IIRC) where the oil that was recommended had PTFE "junks" in it and would continually cause a problem with the injection system. I do not know what they were thinking putting powdered PTFE in the oil. It would plug up the screen in the oil tank fill and you would have to work the oil through the screen with your fingers. My cousins Johnson 225 outboard was changed to pre-mix as I guess the injection systems on those were known to be problematic as well.

Dave

 

[Fish]

yes this was 1

 

[Lakeside53]

What was 1???

 

[Trigger-Time]

yes this was 1

What was 1???

"There were some relevant threads posted/made by Dagger, I will see if I can conjure them up." Fish