Oil in crank/alternator side of engine

[taneglaus]

I’m rebuilding 2 FL350R’s. One of the engines has oil in the crank/alternator side of the engine and no oil in the balancer side.  Any ideas on how the oil migrated from one side to the other side of the engine?
The oil appears to be motor oil and not 2-stroke oil, but I could be mistaken

[LiveWire]

The left crank case is connected into a case void at the front left of the cylinder. There is a small gap in the web of the cylinder between left and right. There is a hole from the right case void into the alternator area. All this was to save adding a separate vent for the counter balancer. There is a recall from Honda to keep the oil level in the counter balancer at the low mark. Honda also describes checking the oil with the dip stick just set in the hole and not threaded in. I thread in and set to the low mark. So even lower yet. I have never seen a worn out counter balancer bearing across not only my own engines, but many I have rebuilt for people. I have always replaced them when replacing the crank bearings since the cases are split.

Honda also added little baffles in the base gasket. If you use an aftermarket base gasket, it does not have these baffles. I suspect with the even lower level I run the oil at, the aftermarket gaskets would be fine.

Some people add a separate vent. I don't bother since I don't have oil migration issues running at the lower level. If added in the wrong spot, it pumps the oil up the vent tube anyway.

[taneglaus]

Thank you for the information. I don’t recall seeing a vent hole but will look more closely. Interesting that I have 2 Fl350r’ s but only 1 has this oil migration issue. We’ll compare the 2 to see if the other case has a retrofit. Although both machines were purchases at the same time from the same Honda dealer back in 85 or 86.

[LiveWire]

The oil was probably over filled on the one with the issue. If you had a brand new machine with the oil at the higher level, the amount that would migrate over is quite small. Once that small amount is lost, you would still be higher than the the Honda suggested level, but below the full mark. The problem comes in if it is continually topped off. If you keep adding, the starter ring gear will pump all the oil into the starter.