1999 YZ 400 milky oil

So i bought this dirtbike a few months ago. The first thing I did was change the oil, flush radiator, etc. The oil looked good when i drained it but went ahead and replace it anyways. So Ive put about 5-6 hours on the bike with no mechanical problems at all. I went to change the oil again last night and it was a little milky looking. Kind of concerned and dont know what to do. I am not losing coolant other than if I fill it to the top and run the bike it drops down about a half inch and then stays at that level consistently. I did get stuck bad in the mud a month ago and had to lay my bike over pull, lay it over pull, and eventually had to be towed out. Im not sure why I would have water in my oil if Im not losing coolant. Should I be concerned or not? What should I look for? Any help would be much appreciated.

O another thing. I seem to be losing oil somehow. I will check the oil level before each ride and I will have to add oil to make it correct. This is each time I go riding...?

If you tried to start the bike in the mud/water hole, it could have drawn water up through the breather hose. 

 

There are only three ways to loose oil:

 

  • Leaks
  • Past the rings
  • Past the valve guide seals

Well it was just mud not any water that I knew of so I dont see how it would have sucked water from the mud. If i was leaking oil from rings or valve guide seals is there any physical signs other than oil level?


And yes i stated it several times in the mud trying to get it out.

Well it was just mud not any water that I knew of so I dont see how it would have sucked water from the mud. If i was leaking oil from rings or valve guide seals is there any physical signs other than oil level?

 

Valve guide seals can produce a single puff of smoke on startup, or as you get back on the gas after decelerating.  Rings cause smoke under a load.  Bear in mind that no smoke may be visible at all and still use oil.  It only takes .0005 cc of oil in the combustion chamber with each power stroke to burn 100cc an hour on average.

ok can we get back to the milky oil tho...Should i be concerned or not? Should I run it a bit then redrain and see if its milky again?

Yes, if there's no sign of coolant loss.

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