What is the proper oil/gas mix for my two engines?

[franchi]

Hi:

I have looked through all of my Lawnboy service manuals but I did not find any fuel/oil misture ratios. I was under the impression that the correct mix for the plain bearing D 400 engine was 16:1. The correct mix for the F engine is 32:1. Is this correct?

Tia,

Franchi

 

[impalass]

Hi:

I have looked through all of my Lawnboy service manuals but I did not find any fuel/oil misture ratios. I was under the impression that the correct mix for the plain bearing D 400 engine was 16:1. The correct mix for the F engine is 32:1. Is this correct?

Tia,

Franchi

The 2 ring piston uses needle bearings at the wrist pin instead of bushings. These bearings did not require the same amount of oil for lubrication and therefore the ratio change to 32:1 .
What is the model number of your lawn boy having the D 400 engine?

 

[franchi]

Hi:

This is what I just learned about my D 400 engine:

It is a D-408 engine

It should have a"one full can of LAWN BOY 2 cycle oil added to one gallon of gasoline.' How much does a full can of LAWN BOY contain?

My engine has needle barings on the armature side of the crankshaft and on the big end of the con rod. The wrist pin bearing is plain. The bottom bearing is a plain bronze bearing.

Do not use 2 cycle Marine oil!

Use only a brand name of oil such as Lawn Boy in your engines. These oils are sold by the manufacturers of 2 cycle equipment. Perhaps Marvel Mystery Oil is also suitable. These cost more but they have expensive formulations!

Klotz products are also good but are very expensive as is Amsoil products.

Extra oil in the mix will NOT raise the temperature of combustion but will cause the engine to run with LESS heat.

Synthetic 2 cycle oils may not be necessary.

Avoid buying oils that have exotic properties or contents advertized on the container.

I can use the heavy oil mix in my F engine without any problems.

As far as improvements in oils over the years are concerned, they have been improvements in sale hype! The products have not improved. As a matter of fact, some are not as good in some cases as the oils in the past! Can one say "Mouse Milk"?"

Stay well,

Franchi

 

[WhyZed]

Hi:
Do not use 2 cycle Marine oil!

Extra oil in the mix will NOT raise the temperature of combustion but will cause the engine to run with LESS heat.
Franchi

Marine oil is fine to use in you lawnboy.
From what I understand of it, it is less damaging to aquatic life then non-marine branded oils. :confused2:

Extra oil 'will' raise the temp inside the engine. The gas in the gas/oil mixture is the internal cooling mechanism.
Less gas = hotter internal temps. More oil = less gas.

Study this hypnotizing link <gif>

[video]http://i48.photobucket.com/albums/f211/justpinit/Arbeitsweise_Zweitakt.gif[/video]

 

[franchi]

Hi Why Zed:

My source of information told me that Marine grade of 2 cycle oils are cut with kerosene to make them less viscous in order to be injected into marine engines. Is this a bad thing? He thought so.

He also stated that more oil provided more cooling. The oil removes much heat in a 2 cycle.

Just his training and experience,

Franchi

 

[impalass]

Hi Why Zed:

My source of information told me that Marine grade of 2 cycle oils are cut with kerosene to make them less viscous in order to be injected into marine engines. Is this a bad thing? He thought so.

He also stated that more oil provided more cooling. The oil removes much heat in a 2 cycle.

Just his training and experience,

Franchi

gas is the cooling factor and oil is for lubrication

 

[franchi]

HI:

Thanks for the reply.

Let me reflect about this for a moment.

Gasoline, cool, is converted ino a vapour, cool, this vapour cools the engine and then is coverted into a hot gas,1500deg.F. The hot gas heats the enngine then is exhausted.

The oil is cool remains a liquid, cool, is heated by removing heat from the engine and the combustion process and then is exhausted. Does the oil add to the combustion temperature when it "burns"? Or is the oil heated to a point that is below its ignition temperature and then exhausted removing engine heat? I do not think that the oil burns in the cumbustion process but is heated to a point where it will smoke, If it burned, it would lose all of its lubricating properties! I have seen engines where the oil had burned causing a breakdown in lubricatiion and there was major engine damage.

In my model airplane engines, oil is used to help cool the old style engines. I run at least 28% oil in the old engines and 18% in the more modern engines. The older engines produce more heat due to their design and the extra oil is necessary to remove this excess heat to avoid engine damage.

These are just some thoughts,

Stay well,

Franchi

 

[impalass]

HI:

Thanks for the reply.

Let me reflect about this for a moment.

Gasoline, cool, is converted ino a vapour, cool, this vapour cools the engine and then is coverted into a hot gas,1500deg.F. The hot gas heats the enngine then is exhausted.

The oil is cool remains a liquid, cool, is heated by removing heat from the engine and the combustion process and then is exhausted. Does the oil add to the combustion temperature when it "burns"? Or is the oil heated to a point that is below its ignition temperature and then exhausted removing engine heat? I do not think that the oil burns in the cumbustion process but is heated to a point where it will smoke, If it burned, it would lose all of its lubricating properties! I have seen engines where the oil had burned causing a breakdown in lubricatiion and there was major engine damage.

In my model airplane engines, oil is used to help cool the old style engines. I run at least 28% oil in the old engines and 18% in the more modern engines. The older engines produce more heat due to their design and the extra oil is necessary to remove this excess heat to avoid engine damage.

These are just some thoughts,

Stay well,

Franchi

Do you build the aircraft and if so how do you store the balsa wood.

 

[WhyZed]

Marine grade of 2 cycle oils are cut with kerosene to make them less viscous in order to be injected into marine engines. Is this a bad thing? He thought so.

He also stated that more oil provided more cooling. The oil removes much heat in a 2 cycle.

Just his training and experience,

Franchi

Hey franchi, I'm no engineer but I know a couple engineers that are less engine and more eer

That could be true, I've never heard that. I have learnt that marine oil has a lower ash content then low performance, low cost, non-marine branded oil.
If marine oil is in fact cut with kerosene then I would consider it an inferior 2 stroke lubricant than what I am using.
Kerosene is a high performance fuel (jet engines, rockets, 2 stroke engines etc), is a every good parts cleaner and is 'oily' compared to gasoline but not nearly as slippery as the 2 strokes lubes I use..

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I agree with impalass, it is the amount of gas in the mixture that is the cooling agent and the amount of oil controls lubrication.

Unfortunately our carburetors are not very adjustable. It is the lack of those adjustments that force us to tune our engines by varying the gas/oil ratios (more oil = less gas to air = leaner) (less oil = more gas to air = richer). It is the ratio of fuel to air that our engines consider a rich or a lean mixture not gas/oil ratios.
My F engine actually has a main jet adjustment which is great (fuel to air high rpm).
My D engines have only an air screw adjustment (fuel to air low rpm) not so great.

We should use the least amount of oil we can for a clean, smoke free, low sent burn.
Only use enough lubricant for what is essential to the internal moving parts and not trying to lubricate your boots, wheel bearings and the neighbors rooftops.

If you must uses a 16:1 ratio using cheap oil and the cheapest low-test gas and find your neighborhood full of smoke after a couple laps of your lawn, then please look into a hotter spark plug. A hotter plug might help ignite the gobs of extra oil that doesn't have the low flash point of the highly explosive gas vapors for a complete burn.

Awe, another reason for using the highest octane gas you can get in every 2 stroke? hrmm..

The ONLY way to really confirm your engine is getting proper lubrication is to open up the bottom end! (There is nothing to lubricate in the combustion chamber). The color/condition of the spark plug determines fuel to air mixture and temperature of the plug.

If your bearings & bottom end are to dry but your plug is wet, add more oil to your mix.
If you bearings & bottom end are to dry and your plug is white (lean), add more oil to your mix and change to a cooler plug.

If your bottom end is dripping wet but your plug is white (lean). Reduce oil, & possibly a cooler plug.
If your bottom end is dripping wet but your plug is wet (rich). Reduce oil, & possibly a hotter plug.

Your temperature and elevation play a major role in how your engine needs to be adjusted.
A perfectly adjusted engine tuned in August at Daytona Beach will run dangerously lean in October in Colorado.

etc...

 

[franchi]

Hi Implaass:

I have not built any model airplanes since 1983. I have over 30 planes hanging in my attic ready to fly when an engine is mounted.

I have stored some balsa in my attic and a number of old kits there also. No damage has happened to either. I also have stored balsa sheets i my basement with no changes to the balsa.

I just got back into flying model airplanes after a stint with shotguns and bird dogs. I still have both. Lol

Stay well,

Franchi