8 replies to this topic
  • Sean Brodie

Posted March 27, 2011 - 02:14 PM


1999 yz 400f have oil coming out of breather tube on valve cover. I just got this bike was this a problem with the 400.:bonk::thumbsup:

Edited by Sean Brodie, March 27, 2011 - 02:52 PM.

  • brentn

Posted March 27, 2011 - 02:33 PM


If oil is dripping out there's a chance that the bike was over-filled with oil. If you get smoke coming out then you got problems.
Check the FAQ for how to do a proper oil level check and see if it is over-filled.

  • Sean Brodie

Posted March 27, 2011 - 02:45 PM


Oil level is in the middle of dipstick and no smoke just lots of oil. Compression was tested by shop thay said it was fine

  • brentn

Posted March 27, 2011 - 04:28 PM


Could be an issue with the drain back to the oil tank from the head. I don't know too much about this area, but hopefully someone with more experience will chime in.

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  • Birdy426

Posted March 27, 2011 - 06:17 PM


Search! This is normal. When you aprk the bike, you will get a bit of a puddle of oil under the breather, maybe an inch or an inch and a half in diameter. You will also get some oil on your left boot. As the engine "breathes", some oil mist is picked up and pumped out the vent along with the air.

  • brentn

Posted March 27, 2011 - 06:30 PM


Is this a normal 400 thing, cause it never happens on my 2010??? :thumbsup:

  • DeeCee

Posted March 27, 2011 - 07:12 PM


My '98 YZ400 always has a small drip of oil after a ride, same as Bridy 426 says. I never have to top the oil up beween changes which shows the amount of oil 'lost' is minimal. In fact I would now be more concerned if there was no drip after a ride.

The key point here is, how much oil is coming out. This was not clear in the post.

  • grayracer513

Posted March 27, 2011 - 07:42 PM


Is this a normal 400 thing, cause it never happens on my 2010??? :thumbsup:

The 2010 models have a baffle built into the venting system.

  • spdnjoe

Posted March 27, 2011 - 07:53 PM


Did you start the bike first and check the oil correctly ?
When I first got my 426, the oil was in the middle of the dipstick also, and it had a lot of oil out of the breather tube. but after checking it by the proper procedure, I found out It was WAY overfilled.
Make sure you follow the proper procedures !

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