09 YZ 450 using up oil

My 2009 YZ 450 was just rebuilt last week it runs awesome, I broke the motor in correctly riding it easy for the first hour. After I rode for an hour I checked my oil and noticed it was very low. I put more oil in it (maxima 20/50, same oil i have always used). I rode again last night and did a timed 15 minute moto and the oil was down alot again. Any suggestions on what might be wrong?

I also cant see it leaking anywhere on the outside of the motor.

I checked the coolant for oil becasuse I was told it could be leaking into there and it could be the water pump seal. it wasnt this.

I also checked the spark plug for any oil on the plug. it was a nice grey color

Please help!!

Thank you

I think I know what's wrong: it wasn't rebuilt properly! You're checking the oil level straight after you shut it off?

checked the oil right after i got off the track and again after it cooled down! the bike was rebuilt by a ex factory mechanic!

Yeah, the oil level needs to be checked within a few minutes after you shut it down, and not when it's been sitting for a while or cooled down, because the oil drains away from where the dip stick is(or something like that).

Because the oil tank in the Gen 2 engine ('06+) is so much lower, there is much less tendency for the oil to migrate down from tank to sump, as in the older models. It is still proper to check within a few minutes of shut down, nevertheless.

Riding it easy for the first hour is not really the correct break-in procedure, either. Some significant load must be placed on the engine in order to seat the rings completely.

In any case, there are only three paths out of the engine for your oil:

  1. Leaks, external or internal
  2. Being exhausted from the breather
  3. Oil consumption in the combustion chamber

The spark plug will not necessarily show a great deal of oiliness in a four-stroke, even at a fairly significant rate of consumption. The three primary ways for oil to enter the combustion chamber are past the rings, the valve guides, or the head gasket. It's also possible, though very unlikely, that a crack or porosity problem could cause this. Note, too, that oil passing the exhaust guides does not usually enter the combustion chamber, but goes straight out the pipe. Because of the pressures present in the exhaust, it is less likely that oil would pass the exhaust guides, anyway.

can you suggest what we should do to find where the oil is going? Do we need to tear the motor apart and check anything internal? I have races the next few weekends and don't want to blow the motor! we sent the motor to a mech. down in Georgia and got it back on monday we put it in the bike and went to the track on tues, changed the oil and filter rode again on wed,i did two 20 min motos each day.

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