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6/12/2017
Location
High Lonesome, NM
US
Edited Date/Time
7/17/2019 6:23am
Correct me if I'm wrong, but the flash point of a 2 stroke oil doesn't really affect the bottom end, does it?
In other words, if you ran an oil with a low flash point... let's say, Lucas Semi-synthetic which has a FP of 182 F in a high revving, hard-run 125, it might burn up too fast to lube the top end well, but that wouldn't affect the lubricating properties at the crank, would it?
Awaiting correction/confirmation from my Vital people who Know All Things.
In other words, if you ran an oil with a low flash point... let's say, Lucas Semi-synthetic which has a FP of 182 F in a high revving, hard-run 125, it might burn up too fast to lube the top end well, but that wouldn't affect the lubricating properties at the crank, would it?
Awaiting correction/confirmation from my Vital people who Know All Things.
I think if your top end is dripping oil onto your crank, you need some rings.
The Shop
Thanks!
The Lord isn't helping me so it's up to you. Please explain your thinking here.
This thinking is far too deep for more mortals, even your Lord cannot fathom it's awesomeness.
Explanation is futile, and time is of the essence, for we have migrations to do.
https://m.vitalmx.com/forums/Tech-Help-Race-Shop,42/Two-stroke-oil-ques…
This has always fascinated me as well. I finally wrote to Maxima and got the same sheet as CR250 posted here. The way I am understanding it is that the charge goes into the bottom end, transfers to the combustion chamber, ignites, but some of the oil stays behind and is wipped down the cylinder walls, "migrates", back to the bottom and lubing the bearings at that point. And the cycle continues. At least that is what I understood reading the data sheet. And I am sure as shit not going to argue with Maxima.
Was that how you understood it CR250?
Does this mean a two ring piston will cause my crank to receive less oil than a one ring piston?
It's been said in this thread, obviously the oil enters the bottom end first. Heat, fast moving crank, and whipping motion and atomized fuel helps separate the oil/gas mix, and some oil remains in the bottom end long enough to lubricate the moving parts (crank case, bottom of piston, etc).
Eventually, if jetted correctly and good mix, it will burn off in the crank, or by the obvious moving through transfers to top end, but always have a small puddle at the bottom of the crank from fresh flowing premix. In fact, if I remember right you can actually tell how your bike is jetted by high much residual oil is left at bottom of crank. When you take apart a two stroke you should see a puddle of 2 stroke oil at the bottom. You can also check the expansion chamber header, but actually haven't heard of anyone doing that in awhile.
I know at high load and RPM's, you can actually run low on this residual oil by running a bit lean (sort of explained in Maxima document posted above). I always jet rich enough on top end (AS, Pilot, PJ, needle, taper and main for total fuel) so it's 1-2 sizes below blubbering at WOT. This way there is less chance of losing this oil supply.
Good point; re-reading the data sheet and I can't see where it says that, either. So I looked at the email exchange I had with Maxima and that was where I drew that conclusion from:
~~~~~
"I have attached our oil migration chart. Essentially the oil has a much higher flash point than that of the fuel so after combustion some of the oil is left behind to complete the migration of the bottom end all the way to the exhaust port.
Let me know if you have any more questions and thank you for choosing Maxima!
Sincerely,
(Maxima Oil tech person)
Maxima Racing Oils I ProFilter
~~~~~~~
I pulled the name of the Maxima person so that he does not suffer the wrath of a message board! hahahaha
But yes, your point of how baffling it is, and how it defies logic is valid. I don't get it, either! Maybe it takes a bit for any meaningful amount of oil to accumulate but once it does, it's sort of a matter of keeping the drip-feed fed? But for now I'm going to accept it. Like Mongo said in "Blazing Saddles": "Mongo only pawn, in game of life."
Pit Row
It's an interesting discussion and there's no reason to get any panties in a wad. Wadded panties aren't going to change the facts, whatever they are, which is what we're discussing.
I'd like to know how the oil migration thing is _determined_. Is this a hypothesis or can it be actually documented? I used to work as a statistician for a team of research biologists and it was my job to ask questions like "How'd you get this data?" Just out of curiosity, I'd like to know how Maxima tracks oil in an engine.
“The objective of the premix ratio is to maintain a certain level of “oil-presence” in the engine interior during it’s average “operating-use” cycle. But how does one measure or assess the “oil-presence” … The most effective way has been with a radioactive additive. We explain below.
Trying to keep it simple…here is how it works. A test lab sets up an engine on a dyno stand, and begins feeding the engine a premix of an oil that has a specific level of mixed-in radioactive additive. As the engine is run, a Geiger counter at the exhaust exit measures the amount of radioactive material being eliminated. In this way, it is possible to factor the amount of radioactive material being put into the engine, verses the amount being sent out the exhaust. The net result is the amount of “oil-presence” inside the engine.”
For people to best understand oil migration times, take that 60:1 or 100:1 recommended ratio and go run that down the highway WFO for 3 or 4 miles.
Flashpoint in 2-stroke oils is a.....tricky concept. Most 2-stroke oils are diluted with a solvent and the flashpoint will be directly linked to the particular solvent and how much the dilution is. The solvent does little if any real lubricating and acts as more of a delivery/mixing aid for the actual lubricating portion of the oil.
A few oils are not diluted with solvents and are purely lubricating oil.
Either way, the actual lubricating portion of the oil is what is lubing the bottom and top ends. Because that oil is in solution with the gasoline, the fuel migrating due to turbulence will carry oil with it. The fuel that is evaporating rapidly due to heat, leaves the oil behind for the most part.
The oil left behind and the oil migrating with the fuel will "burn" over time. What makes it into the combustion chamber will burn slower than gasoline, but does burn, and the quality of the oil determines how well ti burns and whether it leaves by-products behind.
The oil in the bottom end will "burn" through evaporation and the rate would be linked to its flash-point (which is not the reported flash point on any SDS if the original product contains solvent). Getting the true flash point of that portion is likely only going to come from the manufacturer unless you want to buy lab equipment and run the tests yourself. I did this for my own company's products and a lot of competitors, and the numbers can vary wildly.
Now, with all that being said, flash point is an absolutely horrible way to judge performance of 2-stroke oils. Unfortunately, it is the most readily available and pretty much the only information we can get from manufacturers because it is mandated by the DOT for transportation/shipping purposes. SO a lot of people attempt to make sense of that number and assign importance to it on its own.
I've said this in many locations and in response to a lot of inquiries over the years and I'll say it again. Picking a single property and assigning a value to an oil based solely on that is a mistake. Aside from how much of the oil will evaporate out of a closed container at a prescribed temperature, the flash point alone tells you nothing helpful in determining how it will perform. There are oils with relatively high flash points that will work terribly. There are some oils with relatively low flash points that will work wonders and vice versa on both accounts.
I absolutely wish it were a super simple thing and we could point to one thing and say "Yes, that means it is good!", but these products are complex and it isn't that simple.
The original question was addressed well by others' comments made earlier and the diagrams regarding oil migration. If anything I've said is wrong or you've got questions, I'll do my best to address it and admit I'm a dummy if that's the case.
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