Get a clean, dry pan and dump your oil. I'd almost bet you won't have milkiness throughout your oil like you should if you have a coolant leak into the oil. If you have a milkshake looking mix, you have a problem. Otherwise I'd pour that oil back in the crankcase and use it. This way you'll know and won't be trying to discern what's up through that sight glass.

 

Well, when I got home this evening, the oil in the sight glass looked normal. I think it was just a little foamy, not water-contaminated. Unless of course the water separated out...would it sink to the bottom or float to the top?

 

If water separated, it would sink. Oil floats on water. But water doesn't separate from motor oil very well in my experience after the motor has ran. It may after a long sit - I don't know. Instead, the oil gets all milky. Take the oil-fill cap off and see if the oil residue on it is clean or milky. A little milky may still be just condensation, but if it's clean, you're likely good to ride without worry.

 

When an oil water mix goes through a trans and engine as ours does it becomes a homogenous emulsion. The oil and water will combine into a chocolate milkshake. I swamped an XR and had to change the oil 3 times before the new oil washed out the old emulsified milkshake.

Just like milk. Water and milkfat will be separate unless they are homogenized and then the milk doesn't separate.

 

Just do what TNC said and drain the oil and inspect it. When ever the engine runs there is some oil frothing that occurs which is normal and what is visible from the inspection sight glass appears as little oil colored bubbles or foam above the oil. It should disappear not too long after you shut the engine off and it cools down.

 

Ok, thanks everyone, that appears to be what is going on with my bike. I have never had one with such a small sump and I think it is just frothing more than I'm used to.