Oil Ratios, Needles and such...

[bigrcr]

On the oil subject;

-Oil in a glow motor has two major functions. The oil lubricates the moving parts (1) and it removes heat from the motor (2). This is the reason glow fuel contains 17-25% oil in it's make-up. The oil is a fluid so it can absorb heat better than a vapor- it carries away excessive heat. There are a few other things the oil does, but that is not part of this discussion. The nitro-methane used also widens the "burn window" for the fuel.

-Oil in a gas motor has one major function and that is to lubricate the moving parts. The oil excess carries little to no heat away, mainly because there is not an excess (at 50:1 there is about 1.9% oil-don't grin guys that use 5 ounces, you only have 3.9% oil). The gas motors don't need the oil amount that the glow motors use since the fuel is not the coolant as well, and cannot be. Gasoline burns in a much tighter window than alcohol as well (air/fuel ratio). That’s mostly why the gas motor needles are more sensitive.

You could add more oil into the mix to aid in heat removal, but the gas motor will not like it, mainly because it operates at a much higher temperature than a glow motor and the oil would start to burn and the excessive oil will foul the plug surfaces. These motors really don't like compressing fluid either so more oil CAN mean more shake and vibration levels.

This is where the oil type and amount comes in.

Petroleum/Mineral based oils: These oils are derived from crude oil or a blend of crude’s and naturally occurring oils . These oils being derived as they are normally would burn along with the temperatures necessary to burn gasoline. HMMMM...not good if you want the oil to lubricate...if it burns up, it won't lubricate and the resultant "ash" would scar your motor. Automobile motors are four strokes and don't use the lubrication oil in the cylinder (it gets wiped off the cylinder to an extent by the rings).
Two strokes pull the lubrication from the motor and compress it along with the fuel contained, using it for fuel. The crankcase in your car does not get hot enough to burn the oil, your 2-cycle motor in your heli brings this oil into the cylinder and tries to burn it. You don't want your oil to burn.

Ashless petroleum oil has been formulated to withstand the temperatures of the 2-cycle motors cylinder temperatures without burning. The flash point has been raised in these oils and impurities that could burn at the temperatures are removed.....Ashless. These oils lubricate well and also allow the cylinder/piston parts to break-in fairly quickly under proper lubrication.

Synthetic oils are not derived from crude oil/naturally occurring oils but are "man-made". These formulations can be specifically tailored (viscosity and flash points mostly) for intended use and temperatures seen in our motors should not affect these oils so that they can do their job.

Too much of these oils and you can foul plugs and raise compression which CAN be detrimental. This can be seen usually as a wet looking plug and can be seen as deposits on the piston and worse on the ring(s) and on the plug as deposits. Reading the plug would include determining if these deposits are from too much oil or the wrong kind or both.

If you are using the right kind of oil, one of the variables is removed and then you are down to looking for too much oil and needle settings.

Air/fuel ratio:

This is NOT the oil/fuel ratio and deals with needle settings, air leaks and to an extent, inherent heat of the motor itself. The 2-cycle motors we use operate at a very specific air to fuel ratio. This is set by the combustion properties of the fuel that we are using (gasoline or Naptha). Gasoline and Naptha burn at VERY close air/fuel ratios (their combustion ratios). The dead on spot within this ratio is where we would like to run, but atmospheric conditions, ignition timing and the motors temperature can effect this. Running the mixture a bit to the rich side will hopefully ensure that the motor is always getting enough fuel in the mixture. When the needles are lean, there is more air than fuel and power goes down and temperatures go up and stuff that would not normally burn, may start to burn. When there is too much fuel in the mixture, power can go down and temperatures can go down (unless there is too much oil- raising compression which could result in temperatures going back up to an extent).
When the temperature gets too low in the motor, it may not be at it's optimum operating temperature which can cause plug fouling, internal scarring (yes- from tolerances not being correct: being lean will do this as well) and needles that are impossible to set correctly due to the motor temperature seeing many changes.

Temperature changes within the cylinder due to a lean condition can be read on the plug as glazing, physical plug damage and a light color on the plug. What you are actually seeing with the white to light grey color is the temperatures burning everything off of the plug and trying to burn the insulator and metal parts as well. The glazing is just that; the temperatures are converting or burning the oil and depositing it as a glaze on the plug. Either way, it's too lean. I could go on about a leak as well, but you should get the Idea.

So reading the plug in our motors is VERY important to do. It is the "check-up" to see "what is really going on" (thanks Beast) inside of the motor and properly reading the plug (and cylinder, piston (exhaust side)) can tell us everything.

There is a very simple and systematic way to read plugs, one day I may have time to put these into easy to understand "layman’s" terms, if I get time. The best practice is to always stay as rich as possible, at least until you really know how to read plugs and such. Tuning by ear is not the best way to do it as it is not a quantifiable measure, the plug is. Even when I tune by ear, I ALWAYS look at the quantifiable evidence (plug, piston, etc) to make sure that the motor is in good health.

[ddavison]

Sent you a email, Dave

[NolanManley]

I remember when I raced Motocross I always tuned by plug readings. Did the same thing on my Honda VTR 1000 when I added a jet kit.

Great info John. THANKS THANKS THANKS. That was a time consuming write-up.

[NolanManley]

Hey John, do you mind if I quote your post at RR on a running post there on Gasser tuning. There are too many leading the blind there. You'll have full credit.

I wait on your decision. If you rather it not be there no problem and I would have posted a link to here but RunRyder kills all links that go to anywhere they don't like. One being here I guess.

Thanks

[bigrcr]

Thanks Nolan and yes, go ahead. It is far more important that pilots learn to properly use these motors.

Later,

[NolanManley]

Thank you John.

[phanislo]

Nice job, but finaly which oil is preffered to be used? Still haven't relised.

[bluepilot2003]

Since I fly airplanes as well with DA engines, I have Redline mixed at the 40:1 ratio. Will that be okay for a TRM 300? Or will I need to up the oil content to not ruin the engine?

[banshee rider]

32:1 is what just about every one runs
The heli engines generally run hotter without that big fan in front of them
hence the 32:1 ratio

[rbort]

Go the other way. I fly airplanes also and used to mix 40:1 for the airplanes and 32:1 for the helis, but now I just put the same fuel in everything, airplanes, helis, weedwacker, whatever, all at 32:1. Works fine for the DA no worries.

-=>Raja.

[Doug Darby]

32:1 is what most TRM owners are running.

[bluepilot2003]

Fair enough. 32:1 mix it will be. Can't wait until early next year when I can get my gasser helicopter going!

[rbort]

The season is here now, if it was winter I'd understand you're waiting for Spring, but waiting now for spring?

-=>Raja.

[bluepilot2003]

I'm waiting now until winter due to a deployment. I would totally just do it now if I were to be around.

[rbort]

Good luck, stay safe, and thank you for what you do for us!

-=>Raja.

[jharkin]

Originally Posted by rbort

Go the other way. I fly airplanes also and used to mix 40:1 for the airplanes and 32:1 for the helis, but now I just put the same fuel in everything, airplanes, helis, weedwacker, whatever, all at 32:1. Works fine for the DA no worries.

-=>Raja.

I missed this thread, but +1 to this recommendation.

I have a single can of 32:1 mix that runs in:
Hanson 270
Hanson 300
DA50 (been running this engine 9 years on this mix now)
soon DA35
Husquavarna chainsaw
Husquavarna weed trimmer

And even more shocking I run conventional oil! and nothing has exploded in a ball of flames

Never had a problem with anything. More oil wont hurt other than maybe needing to pull the jug and scrape carbon a little sooner.


If you are curious - The photos below are what my DA looked like when I pulled the jug after 7 years of running on 32:1 penzoil air cooled. Note that older DA50s tend to have a very fat midrange (hard to tune out without getting into running problems since they had a batch of bad carbs where the hi needle could not go rich) and plane engines spend a lot of time in the mid so they get a lot more buildup then a well tuned heli engine should.

The carbon was all soft and easily wiped off, the last picture you can see how the jug looked after I cleaned it. (just wiped out with a rag )

off topic: I eventually found a fix to the fat midrange problem on my 50 by swapping to a different carb with a larger main jet so I could set the hi needle a little richer and safely lean out the midrange. I expect it will look a lot better at the next 7 year clean out

[Toxic Al]

Mixture ratio is more based on the oil formulation certain oils do not like to be mixed rich and some don't like to mixed lean, amsoil saber is designed to run leaner on the mix and if used to rich will get sloppy and could gum up the pipe and ring, I run it a 40:1 after breakin in my engines. whatever oil you use stick with after breakin and fine tune the mix as you go. Peace, Al

[rbort]

Amsoil at 40:1 is still not good, makes carbon in the engines. I flew that for some years but try Penzoil Marine at 32:1, you will find its better and cleaner on the insides of the engines.

-=>Raja.

[Toxic Al]

Maybe in your engines, I have never had an issue in the 11 years I have been using it and I tear down my engines for inspection and have been very impressed with the results, If you like Penzoil then by all means use it it is good oil.

[crma0101]

Al,

I have both Amsoil and Redline oil easily available ( have both on hand ) still waiting on my TRM 300TT special edition for my first gasser heli build this winter, after reading this I will say I ran the Amsoil in my DA-50 for 5 years and never took the engine apart at all, ran great, but I would get a little carbon build up just at the end of the exhaust pipe and some black spots on the landing gear right where the exhaust flowed around it... was told my some they ran the redline at the 32:1 vs the Amsoil at the 45:1 I was running in the DA 50 and had not seen the same spots or build up, so I was thinking of using the redline 2T racing oil in my first gasser heli after break in... sounds like you are a very big supporter of the Amsoil - do you feel one is cleaner running than the other, I think both are good oils... but want to pick one and stick with it.
thanks.