Bill O'neal....
I made a mistake, it's on the PTO side, not the MAG side. The rear bearing on the CB shaft is not a sealed bearing and therefore, the oil not only lubricates the gears it also lubes the rear bearing. Also, there are no seals on the crankshaft to keep the oil from the crankcase and the oil will seep through the crank bearing.
Chester
I have nothing but high regards for Bill O'neal and for all he's done through the internet to help others understand the working of our Rotax engines and helping people to understand it to a degree, they feel comfortable in working/repairing it.
Like I stated before, I believe we are all like a finger print, we as humans are all different and perceive things in different ways. Some of what he states is accurate, some I still don't totally agree with. If I had not attended so many schools in engineering theory and principle, I might be easier influenced.
This will be my last reply to this post due to the topic not being covered in depth or to the degree that could eleminate differences of opinion in our shop manuals. I have also not been able to find any conclusive evidence from BRP stating one way or the other, exactly how this area is lubricated. What I am describing is my theory after tearing this engine down and anaylzing it. By far am I saying that my theory, is absolute.
If you look at the pix attached by the member of the balance shaft area. You will see the hole from which we fill that one ounce of motor oil (in later models, BRP suggests injection oil). It's internally ported to the back side of the PTO area of the casing, kinda behind the cylinder skirt.
Although I do see this hole as a way to maintain oil level, I don't think it's capable of allowing the oil to be burned off from inside the CB area. Why? The flash point of the oil and gas mixed is not the same. The fuel (gas) has a flashpoint around 90*F. The oil has a flashpoint that is much higher, about 180*F. So, during combustion, the oil/gas ratio is designed to burn off the fuel and oil because those temps in the combustion chamber exceed that. But, in the area of the crankcase, during delivery, the fuel begins to vaporize as it's making it's way to the spark plug. Some of the oil is seperated along the way and remains a liquid and is used to lubricate the bearings before finally being burned off. If you open a Rotax engine that has been in use, the day of or shortly after, you'll find an oily film that remains. This should lead to the idea that not all oil is burned off from injection. Now, if you look at the idea that this oil covers the entire area of the crankcase, it seems logical that gravity would capture some of this oil as it runs down toward the bottom of the motor, find it's way into that hole, which is oriented in an up/down direction and dribble oil into that chamber. That, I agree to.
But, for that oil to be burned off, that means it would have to go against gravity and climb upwards into the PTO cylinder (which viscosity and weight doesn't seem to favor oil moving upward), fall into the casing area and mix with fuel. I don't see this possible. Here's why. Your statement that the oil/fuel mixture passes through the crankcase bearings isn't completely accurate. If you'll note in the pix I've provided, you'll be able to see this. Looking at the counterbalance shaft, you'll see two rubber seals, identical to the seals in our jet pump, without the metal casing. Their design along with the spring, are there to support a tight seal. It appears to be more hermetic than the bearing seals at the crank. If not, then you could assume that if oil is leaking passed them, the same would be true of our Jet Pumps.
If you look at the crankshaft really well, you'll notice there is a closed bearing design on that side of the crank. The roller balls of the bearing are only exposed from the inside crank casing area, not from the balance shaft area. You can also see that thin washer looking piece. This does not have any holes in it for oil to pass from between the crankshaft area to the CB area. The roller bearings from the inside area of the CB cavity are open to the oiling side of the reservoir. So, that would lend credence that those outer bearings are lubricated but backed by a seal, so the oil is not lost from that void.
The engine sits in position relative to the hole at a degree, which is somewhere along the lines of 12 to 14, I'm sure that is documented somewhere, I just don't have that fact easily available while doing this reply. So, that would leave the 1 ounce of oil, moreso in the balance shaft side, than the crank side. In saying that this oil migrates from this cavity into the crank casing, seems all but impossible when you analyze it, though it doesn't mean that this cavity does not have additional oil enter the void via the internally ported hole from the upper part of the PTO side casing.
This CB area is exposed to the pulse pressure of the engines operation but I don't think its capable of filling this void with oil. If there were two holes, one top, one lower, then you could say there was circulation. But as it is, it's more of a dead pocket, seperated from air and oil flow of the casing. If by some chance oil did circulate into this area regularly during operation, I know from experience, that the friction created in a totally submerged set of cog gears, would be so great it would not be capable of turning the high revolutions these engines turn. .....
I've tried to take some pix of my older motor. I have yet to rebuild it because I have no real need for it yet. And the truth of the matter, I have two kids that come before my toys and my wife would shoot me if I did. I have been buying parts for it over the last year, one by one....:rofl:
Not only do I highly respect Bill O'neals work on the internet but I too respect yours (Chester) and other mechanics in our forum. I know you say you've built many motors over. But, the next time, look at the bearings inside the motor, how their rollers are exposed to lubrication, then look at those in the counter balance area and note, they are closed. Like I've said from the beginning, this is not a hermetically sealed area, but it is a seperated area inside the engines casing.:cheers:
I was seeing something that I could not understand It apears that their are 2 places for crankcase pressure and atomized fuel to enter or leave this cavity. They are both located within a couple of millimeter from one another. 1 hole that Louis has pointed out and another that is between the labyrinth washer and the bearing that resides with it. There is about .010 inch clearence all the way around the labyrinth washer and the bearing. I am trying to figure out what is keeping the atomized fuel oil mixture from washing that oil from that cavity. I have seen many engines that have less than .006 of a inch clearence between piston and cylinders and that mixture always seems to find its way between there. If you can help me to find away to keep the oil in the cavity I sure would apreciate it,other wise I may have to add a fill plug so that i can keep adding oil so that I do not burn things up.:stupid: :agree:
