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2016 yz250f milk oil smells like gas

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Walked passed my bike that other day looked in sight class and noticed it was milky colored. Changed the oil and filter and the oil smelled of gas. I last time I rode the bike was in about 40 degrees f. I say this because one guy said it could be over fueling in the cold. Is it cold enough to do that? Or should I look into new pump/injector 

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If oil looks milky that usually means coolant has got into it. That could be a leaking head gasket or failed water pump seal. You could check how much coolant you have, see if its low and check if it looks contaminated.

As for fuel getting in the oil that might be a bad injector, fuel pressure regulator, spark plug, or the sensors that control fueling like the air pressure sensor, etc. Not the fuel pump.

Did you notice your bike making smoke?

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Failed water pump seals leak out of the weep hole and not into the crankcase so milky oil is from a failed head gasket, cracked head or cylinder, or leaking welch pulg if these motors have them

Edited by GuyGraham

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6 hours ago, Wait-A-While said:

If oil looks milky that usually means coolant has got into it. That could be a leaking head gasket or failed water pump seal. You could check how much coolant you have, see if its low and check if it looks contaminated.

As for fuel getting in the oil that might be a bad injector, fuel pressure regulator, spark plug, or the sensors that control fueling like the air pressure sensor, etc. Not the fuel pump.

Did you notice your bike making smoke?

The coolant is fresh and the mark hasn't changed at all.Yes the bikes been burning a good amount of blue smoke recently. I've been figuring the fuel has been drying out the cylsnder walls and causing the ring not to seal.

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41 minutes ago, willmud743 said:

The coolant is fresh and the mark hasn't changed at all.Yes the bikes been burning a good amount of blue smoke recently. I've been figuring the fuel has been drying out the cylsnder walls and causing the ring not to seal.

That makes sense. What does the spark plug look like? I'm thinking it should be pretty fouled. 

But you also have milky oil.

I had a car that started running a bit rough and reeked of fuel at times. It had a head gasket fail so bad that the coolant hydro-locked the engine when I tried to start it. When I drained the coolant it looked nice and green, when I drained the oil it looked black. Go figure. I'm still not sure if the fuel smell was caused by incomplete combustion or a pinched injector o-ring. 

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1 hour ago, Wait-A-While said:

That makes sense. What does the spark plug look like? I'm thinking it should be pretty fouled. 

But you also have milky oil.

I had a car that started running a bit rough and reeked of fuel at times. It had a head gasket fail so bad that the coolant hydro-locked the engine when I tried to start it. When I drained the coolant it looked nice and green, when I drained the oil it looked black. Go figure. I'm still not sure if the fuel smell was caused by incomplete combustion or a pinched injector o-ring. 

That's the thing the bike runs awesome. It starts up first kick from dead cold but. I haven't checked the plug or anything yet I need to dig into it tonight. I'm putting a new top end on it soon but I just perplexed by the issue I'm having and I wanted to get a few more rides into before it's too cold and I have the thing apart

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So you have a bike that runs like a top but is dropping hints that it might have serious problems. Hmmm.

I just thought of something else, if you take the bike for short rides in humid conditions it can cause a lot of atmospheric moisture to condense and end up in the oil causing it to look a little milky. Might that be the cause? I live where it's extremely dry so this problem is only one I've heard about, never seen. 

I'd be worried about that fuel wash wrecking the cylinder surface. It wrecks iron bores, I don't know how bad nikasil is affected. I know that 2T riders have that to worry about it because it can cause a seize.  

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25 minutes ago, Wait-A-While said:

So you have a bike that runs like a top but is dropping hints that it might have serious problems. Hmmm.

I just thought of something else, if you take the bike for short rides in humid conditions it can cause a lot of atmospheric moisture to condense and end up in the oil causing it to look a little milky. Might that be the cause? I live where it's extremely dry so this problem is only one I've heard about, never seen. 

I'd be worried about that fuel wash wrecking the cylinder surface. It wrecks iron bores, I don't know how bad nikasil is affected. I know that 2T riders have that to worry about it because it can cause a seize.  

The last time I rode it before I was riding in some snow. But I I checked the filter for snow before I parked it. But i have not ridden the bike after i discovered this issue i hosted started once after the oil change to see how the oil looked

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