Capp-oil-ccino?

[MisterCinders]

Tried searches for this, but it's a pretty odd thing to describe.

I recently changed my oil and filter after some carb overflow problems. Not sure the oil really had any gas in it, as the level did not increase dramatically and the overflowing happened during test starts and a single ride around the block. In other words, it wasn't sitting around seeping into the crankcase.

But whatever, better safe than sorry, so new oil and filter.

Now I have the carbs pretty much sorted, and have been fine tuning the synch and pilot circuit in the garage (with a fan blowing). So the engine has been running for short periods at idle and at about 2500 RPM, but nothing under load yet.

So far so good, but I noticed something odd in the oil level sight window. Stupidly, I didn't think to snap a picture, but here goes.

In the window I can see the oil level sitting nicely between the F and L lines shortly after shutting down the engine. There seems to be a layer of white/tan film about 1-2mm thick on top of the oil. It looks like side view of a cappuccino.

What the hell would cause that? Sure, I can change the oil and filter yet again . But if there is something else going on, I wanted to figure that out before I keep burning through oil and filters.

TIA

[Big T]

Water condensing in your crankcase. It happens when the bike sits and/or is used for short rides only

Take a nice long ride and it'll disappear

[rustybronco]

There seems to be a layer of white/tan film about 1-2mm thick on top of the oil. It looks like side view of a cappuccino.

What the hell would cause that?

The crank spinning through the oil in the crankcase, oil circulating through the engine, cam beating the tar out of the oil, transmission gears ect. That's the reason for putting anti-foaming agents in motor oil.

I suspect it dissipates after a few minutes or so?

[MisterCinders]

Haven't ridden or run the bike enough to see if that changes things. Glad to hear it's not ectoplasm or a symptom of some other engine horror.

The testing and idling is otherwise going well, but I was nervous about taking it out and putting the engine under load if that foamy stuff was some portent of disaster. I'll keep an eye on it and see if it fades out after some real use.

Thanks.