cylinder head breather tube

3 replies to this topic
  • mat

Posted October 29, 2001 - 12:03 AM


does anyone know how to stop the cylinder head breather tube from spitting out oil, i manly ride desert, for long periods of time and it seems like everytime im done theres some on my skid plate, could this just be from the high temps in neveda,

  • sirthumpalot

Posted October 29, 2001 - 02:44 AM


From what I understand this is normal. I only ride MX and mine does this too. Not sure how you can stop it short of putting some type of catch bottle on it with an air filter on the vent (to keep dirt out of the collected oil).

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  • DaveJ

Posted October 29, 2001 - 03:21 PM



Sirthump is right, this is normal. Most closed system, say in an auto, re-route this back into the intake manifold. Most race applications run it into a catch bottle.

Some of the guys on the board have done something similar to this to make the bike a bit more water proof since you can get a vacumm on the hose at certain times.

If it's getting excessive, you may want to do a compression check on the bike.


  • techman

Posted October 29, 2001 - 07:30 PM


My YZ finally went low on compression (I could ooze the kickstarter past TDC without decomp) and it turned out that a hone and rings fixed it easily. Point being, I was noticing a non-zero amount of oil on the foam filter at the end of my breather tube, which never used to get oily at all. Probably because of the extra blowby. BTW, my breather tube goes uphill from the engine so oil can run back into the cyl head if there's not too much blowby outflow to send it out the open end.

It took about 70 tanks of gas to attain that state. Valves were still good and in adjustment!!

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