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gas : oil ratio for craftsman weedwacker


James Sanders's Avatar
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04-08-06, 12:15 PM   #1  
gas : oil ratio for craftsman weedwacker

what is the correct ratio for a craftsman weedwacker C944-517360?

i believe its 50:1, just want to make sure

 
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04-08-06, 06:52 PM   #2  
50:1 should be ok, I'd use 40:1, just a little more oil anyway.

 
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04-10-06, 03:05 AM   #3  
Provided the engine has had time to "break in" I can't stress enough the benefits of synthetic oil in two-strokers. And then you mix the fuel/oil at the oil manufacturers recommended ratio...not necessarily the engine manufacturers suggested ratio.

 
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04-11-06, 01:13 PM   #4  
I run all my 2-strokes on 40:1 mix. I do NOT use synthetics.

I fly model airplanes that have gasoline 2-stroke engines ranging in size from 25cc up to 100cc twins. I will NOT use a synthetic oil in my engines. I run them all on 40:1 oil and I punish the heck out of them. No signs of unusual wear on any of them.

IMO--synthetics is just myth and hype to sell you more expensive oil that you don't need. If you just run a regular old dinosaur oil in your engines, and mix it according to the label on the oil bottle--you'll not have problems.

As for ratios:
If your not fouling plugs and getting gummed up rings or carbon deposits in the combustion chamber--then your fine. More oil is better--but only to a point. 32:1 is about as rich as I'd go. Anything more than that is for really punishing conditions where circulated cooling air is minimal and engine revs are excessively high.

40:1 is usually the standard. 50:1 is okay, if the oil manufacturer designed the oil to run at that ratio.

Mixing 40:1 oil at 50:1 is a good way to cook your engine.

You can run just about ANY oil, so long as you mix it according to the label on the oil bottle.

DO NOT use 2-stroke oil for boat motors. Boat motors are water cooled. Thats different oil.

Weed eaters, chainsaws, snow blowers, lawn mowers, airplane engines are all air cooled. Different oil.

 
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04-11-06, 01:23 PM   #5  
Synthetics withstand the higher heat in air cooled 2 strokes better and longer..., synthetics will also smoke less, and leave much less deposits, Btw, most synthetics will most certainly improve the power in a 2 stroke, mostly to do with its flashpoint. As for 40:1 mixed at 50:1...what does this mean? If multi ratio 2 cycle oil or pre measured 40:1 is measured out to 50:1, and its gonna be used in a engine spec'd to use 50:1, this will not burn it up. Also would like to add, engines running with 32:1 and engines run with synthetic out to 100:1 didn't show much difference in wear.... which means the synthetic did the job better, at a lighter ratio. This is no hype.... try some mobil 2t and you'll like it as well...

 
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04-11-06, 01:40 PM   #6  
I disagree.

I see the insides of engines all the time. I fly airplanes with a bunch of guys. I have seen the insides of enough 2-strokes to know that synthetics don't hold up as well under punishing conditions as non-synthetics.

You do what you want, but unless you have actually SEEN the insides of a 2-stroke engine after being run on synthetic oil for a couple hundred gallons--then your just repeating what you've heard and read someplace else.

I've had engines apart. I've seen all the piston skirt scuffing and carbon build up from using synthetics. I've seen the pitted pistons, and burnt rings.

I've got a 52cc airplane engine here that I've run 126 gallons through on non-synthetic oil at 40:1 and it looks beautiful inside. The piston skirt doesn't show signs of scuffing. There is barely enough carbon in the combustion chamber to even scrape out. The rings are free and not gummed up. Compression is still very good. I expect this engine to go well over 250 gallons before I might think about replacing the rings.

I've seen 50cc engines run at 50:1 and 100:1 on synthetics and they look like someone threw sand in the intake after only 20--30 gallons.

The comment about mixing 40:1 oil at 50:1 oil means that if the label on the bottle says to mix the oil at 40:1--and you mix it at 50:1--you risk cooking your engine.

I'll stick to non-synthetics, because I've seen what synthetics will do to an engine.

 
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04-11-06, 05:34 PM   #7  
Exactly what brand synthetic was used then?.... and as for 40:1 used at 50:1..... just think about that for a minute... the same oil as in 50:1, but pre measured out to 40:1, and measured out to 50:1 to be used in a engine that specs 50:1.....
and I have seen what synthetics can do.....

 
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04-11-06, 08:17 PM   #8  
Posted By: v8driver Exactly what brand synthetic was used then?.... and as for 40:1 used at 50:1..... just think about that for a minute... the same oil as in 50:1, but pre measured out to 40:1, and measured out to 50:1 to be used in a engine that specs 50:1..... and I have seen what synthetics can do.....
Your making it too hard.

All I'm saying is don't take an oil thats formulated to work at 40:1---and mix it 50:1. Thats all.

It makes no difference what the engine manufacturer says. You mix your oil according to the label on the oil bottle and it will work. If the manufacturer of the engine tells you to use 50:1, there's no reason why you can't buy an oil from, say Husqvarna, thats designed to run at 40:1 and run that in your engine at 40:1. But, if you take that oil thats designed to provide protection at 40:1 and you mix it 50:1, your going to have problems.

What synthetic? Amsoil

 
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04-12-06, 01:12 AM   #9  
Ok, this thread is getting off course, but I will step in here and put in my two cents worth. I agree with Puey61 and V8driver. In every application I have seen, synthetic oil seems to have no negative effects and usually has benefits.

The logic that more oil is better is false, and I bring this up only so that other members do not follow that advice. The richer the oil mixture, the lower the flashpoint of the fuel, so you get less efficiency and more slobber out the exhaust, more carbon in the engine, and a dirtier running engine. Also, the oil that is pre-measured in a 40:1 bottle is the exact same oil that is premeasured in a 50:1, or 32:1 or whatever ratio bottle. They just do the measuring for you and sell you little bottles for more money. I buy mine a quart at a time and mix it myself.

I can see you may have had some engine durability issues that you are associating with synthetic oil. There are many other variables you may not be accounting for, especially since these airplane engines you are comparing to are apparently not yours and not under your constant supervision.

All I'm trying to say is that you have stated some questionable "facts", and we here are professionals in this trade, and owners of small engine repair shops, and have surely seen more 2 strokes and the results of synthetic oil than you have as a hobbyist. No offense intended by that, and I hope you don't take it. Just putting credentials in their respective places.


"Who is John Galt?" - Ayn Rand (Atlas Shrugged)

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04-12-06, 02:56 AM   #10  
I hardly do anything other than build, repair, test and have others test 2 stroke engines for a wide variety of purposes and under a wide variety of conditions. "High Quality" synthetic oil mixed at the Oil Manufacturer's spec's is best. What brand engines are you primarily running Chris? I do see some interesting conflicting data when running Zenoah engines with a tuned pipe. I also see conflicting data with all type engines operated without spark arresters using non-synthetic oil when the mixture is plussed by 8% over manufacturer spec's. I can't stress enough how much slobber effects the operating efficiency of these 2 strokes. I suspect Chris, your running almost clinically perfect engines as I do in the R/C boats. I tear them down at least once a month but if I were flying, I'd probably tear them down more frequently. I suspect we might all agree given identical engines under the same operating conditions? But then again...maybe not? Everybody has one and this is my opinion. Thx, Ron

 
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04-12-06, 10:32 PM   #11  
I'm running all different brands of engines in my planes.
Zenoah, DA, 3W, Fox, Brison, Even a converted Ryobi 31cc weedeater motor in 1 plane.

It's not my intention to cause hard feelings here.

Read this page. This guy has done extensive testing with all different types of oils and all different ratios.
What I gather from it, is that synthetics burn up and cause carbon deposits.
http://www.geistware.com/rcmodeling/...test/index.htm

And you can read this page for detailed discussion on the results:
http://www.rcuniverse.com/forum/m_26...%2Ctest/tm.htm

Just putting the information out there for anyone interested in hard data.

 
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04-12-06, 10:34 PM   #12  
getting back to the original point

the oil i use can be used 50:1 according to the oil manufacturer.

how much oil in ounces (oz) goes into 1 gallon of gas (5 litres)

2.56 oZ?

 
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04-12-06, 11:33 PM   #13  
James, it's not critical to get it down to the hundredths. I add 3 ounces of oil to 1 gal for units taking 50:1 ratio.


Chris, No hard feelings here. I just re-read my post and it doesn't sound quite like I meant it to. Feelings aren't always conveyed easily through written text. Especially when you're trying to disagree. Part of it is also because I am/was trying to stop this thread from veering farther from the original topic and question asked by the author.

I will add that I do not and never have worked with RC model engines. I am aware of some tests performed with husquvarna equipment, running their engines as lean as 100:1 with synthetic oil with superior results. I don't have any of the resulting data anymore though.

I'll take a look at the links you posted. It's going to take a lot of convincing data to change my take on this subject, but I've been wrong before...plenty of times .


"Who is John Galt?" - Ayn Rand (Atlas Shrugged)

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04-12-06, 11:40 PM   #14  
3 sounds safe for me. i think i've been putting 5-6 ounces in and it smokes when i start it up. i'll try it a bit leaner once this can is empty.

 
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04-13-06, 12:07 AM   #15  
Chris, I looked at the tests on the link you provided. There were far too many variables and not enough tests for each scenario to form a theory upon. The air temperature alone can change the results. The air temps were varied, but cold, which contributes to carbon buildup anyway, and engines generally don't run as efficiently in cold weather.

I also see that these engines are run under very different circumstances than weedeater and chainsaw engines. These planes seem to run under a good load at a decent rpm most of the time, while saws and trimmers are revved up and down constantly, and spend a lot of time idling. Maybe certain oils lend themselves to certain running conditions.

I noticed the guy performing those tests actually sounded like he expected extra power to be produced by the combustion of the oil?? It sounds as if he thinks adding oil should require leaning the high speed adjustment a bit moreso than if he were running straight gas...like the oil is making the gas more volatile? That's backwards.


"Who is John Galt?" - Ayn Rand (Atlas Shrugged)

God bless!

 
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