2012 CRF450R Oil in Airboot

8 replies to this topic
  • crfgoon428

Posted October 11, 2012 - 03:09 PM


I have a 2012 as stated and it is right at 30 hours. Used correct break in procedure and changed oil ever 4 hours engine and tranny.

I went to change my airfilter before practice and the whole bottom of my airboot had a layer of oil the whole way across it. so i cleaned ot the oil and changed the filter and went and rode some more and it happened again?!

What could this be, my suspicions could be that i have a FMF rct 4.1 and a megabomb with out mapping causing to much blowback? Or could it be that a valve seal is out or a possible injector?

Anyone else have this happen or know what it is?

thanks ahead of time for any replies


Posted October 11, 2012 - 04:11 PM


You are probably not draining all of your oil out when you change it, so when you re-fill it you are ending up with too much oil.

There is a vent on the top of the valve cover that vents directly into the airboot, before the airbox.

When you reach high rpms you push up the oil pressure, and the oil has to go somewhere, if there is too much....

Mapping, injector, pipe, have nothing to do with it.

Edited by Krannie, October 11, 2012 - 04:15 PM.

  • crfgoon428

Posted October 11, 2012 - 04:21 PM


I always check my oil level before i ride and it was perfect both times so im not sure what it is. Would that harm the motor in any way though to be sucking oil? I was going to race it this weekend but if its going to end up worse ill just run a smoker


Posted October 11, 2012 - 05:43 PM


I always check my oil level before i ride and it was perfect both times so im not sure what it is. Would that harm the motor in any way though to be sucking oil? I was going to race it this weekend but if its going to end up worse ill just run a smoker

What do you mean you check your oil level....with the dipstick?? That's about + or - 15% or so.
You have to measure it in, and get the motor HOT when you drain it, and kick it through 10 times to get it all out.

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  • crfgoon428

Posted October 11, 2012 - 05:47 PM


Ya with the dipstick and its always right at half way so i dont think its over filled i read somewhere else there is a T in the line amd ypu might have to pull the plug out.....maybe doing a vacume type thing

  • emerybrian

Posted October 12, 2012 - 09:35 AM


I found that running the bike on it's side or upside-down (like after a fall) made this happen. Several times I lost a substantial amount of oil to where it came out through the airbox onto the swingarm and once onto the exhaust. I bought this kit that won't stop the oil coming out, but atleast now it will stay out of my airbox.


  • crfgoon428

Posted October 12, 2012 - 01:35 PM


I had not layed it over either time i meai was mostly on a turn track but still it shouldnt have done it afyer that. I think i figured it out i pulled the plug out of the over flow hose above the front sprocket and about am inch or 2 up the line was like someone stuffed grease in there so im wondering if that didnt have something to do with it......i read on another thread to try that

  • HONDA500AF

Posted October 13, 2012 - 01:25 PM


I guess to me it would depend on how much "oil" was actually collecting in the boot. I have something like 23 air filters for my 09, so I change them regularly. It has 396 hours on it. Every time I can remember, when I change the filter, there is a layer of oilly scuzz that is sitting in the air boot. Personally, I don't think there is much to worry about, I have always assumed it was a combo of "blowback"/air filter oil/ whatever. That being said, I know there was one time my bike spent a minute or so upside down and when it got righted, most of the oil came out of the airbox. So much so, that we had to go get more oil before I felt comfortable running it. Hope some of my rambling is a help.

  • crfgoon428

Posted October 13, 2012 - 02:17 PM


Holy shit 396 hours!!?? Thats impressive and we thought i was mostly blowback with a small amount of overfill from the crankcase. We are raczing it tomorrow so i guess we will find out tomorrow. But when i opened that plug on the end of the T there was like a grease that came out......cant be healthy. I also cant see any large failure, it only has 30 hours since april

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