Re: Mercury 25hp - How do I tell whether it is a 2-stroke or 4-stroke?
You can lean out a motor with using too much oil in the mix... I think. Here is my rational. The carbs are only going to pull in a set amount of a premixed liquid; the more oil in the mix the less gasoline there will be. Therefore not allowing enough fuel into the cylinders and leaning out the mixture and raising the combustion temperature. Because the oil does not burn nearly as efficiently as the gas it will not consume the O2 in the cylinder like the gas would... therefore again raising the oxygen to fuel ratio and making the mixture lean. Granted engine damage is probably only going to be caused by either extremely heavy mixtures or prolonged running at a high ratio but either way the final situation is a high combustion temperature, increased carbon build-up, and eventually failure of the piston or rings aka a lean running condition.
But I will stand corrected, lean conditions do melt the pistons not the cylinders.
These two things seem mutually exclusive to me.
Fire requires three things to burn: Oxygen, fuel, and a source of ignition. Just becuse the fuel source is inferior, does not mean that the oxygen available will not be consumed. I understand your argument, I just believe you are incorrect. Obviously, I have not researched to find a source to prove that, I, like you am just going off of my (limited, of course!) experience and education on the subject. I see where you are going with it, but keep in mind that we are not talking about an unlimited space here, and, if anything, the oil, being more dense than gasoline, may actually be reducing the amount of available oxygen in the detonation area at the time of spark. What I'm trying to say is, yes, there is les gasoline present, but it was
replaced by oil, so why would there be any more
oxygen available?
When you buy a new two stroke engine or have one rebuilt, the engineers and mechanics that design and build them advocate this during the break-in process (doubling oil ratio, that is). Hard for me to beleive that is incorrect procedure given the # of times I have been told to do it.
Not to mention, the oil is what acts as the lubricant. That means that the failure to burn off ALL the oil upon detonation is going to leave oil behind, and it is stilll going to act as a lubricant.
I will certainly agree that over time, carbon build up is going to be a problem, but it is a problem that manifests itself in these types of engines anyway. You would just be speeding up the processs.
Keep in mind that I am not advocating this as a long term fix, but if I had an older motor and I suspected or knew about slight piston/cylinder damage (as is probably the case in this guys situation) I would most certainly do it for a short period of time hoping it helped remedy my situation.
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