Is anyone re-routing the cylinder head breather hose?

12 replies to this topic
  • Joe_P

Posted April 21, 2004 - 07:08 PM


I've decided to re-route my cylinder head breather hose. Mike Hobbs on suggested doing this in case you stall while crossing some water. I personally don't have the opportunity to cross water very often, but I've pulled the hose off the head and noticed dirt clinging to the inside of the hose closest to the head. Who knows if any made it into the engine or not. Most likely nothing has since the bike is running great, but it seems like this configuration leaves the engine vulnerable to debris. This may be blasphemy, but a friend of mine ordered the plumbing from a CRF450 and put that on his WR450 and said it works great. It's a clean design and guarantees that dirt won't make it into the engine. I've decided to go this way, also. Parts totaled $40. I guess I could have gone cheaper, but my way probably wouldn't have been as clean. I haven't had an opportunity to check out what the fast guys are doing (if anything). Any suggestions (other than kicking me off the forum for suggesting honda parts) are appreciated. I haven't come across any threads in the forum about this subject. If there are, please direct me to them. Thanks.

  • eightarches

Posted April 21, 2004 - 07:13 PM


I've considered it. Once I thought it would be a good idea to clean off my bike in the river prior to loading up. End result was water in my oil. Don't know how it got in but I suspect the breather hose.

  • sabin

Posted April 21, 2004 - 07:39 PM


OK, I was skeptical about getting dirth in the engine from the breather, but I got my flashlight and looked in it in the side of the engine and there was dirth all over it, so I guess dirth gets in the engine...

  • eightarches

Posted April 21, 2004 - 07:40 PM


Tell me about this CR mod. Aren't there any filters to keep dirt from getting sucked into the crankcase?

  • RatRacer

Posted April 21, 2004 - 09:22 PM


Apparently there is some type of foam inside the line to act as a filter in the CRF's?! I'll let you know once I look at one tomorrow.
There is an even better mod involving a re-route to the airbox, just make sure you loosen a screw or put in a drain hole in case you get some water in there as well!

(I just shortened mine for now.)

  • The_Missile

Posted April 22, 2004 - 12:51 AM


This was thrashed to death months/years ago.

The breather will SUCK water & crud if you try and start while the breather hose is submerged.
When running it suck/blows repeatedly a small amount very fast. Oil foam is known to drip in varying quantities.

- many just reroute the thing upwards
- many also put a T joint just above the head cover and route 1 pipe to the airbox and leave the original one where it is. If the bottom one is submerged the top one can breathe. Some worry about excessive oil getting into the airbox. I have this and have 0.
- many put bits of foam in the pipes to stop crud getting in them.
- also to do....route 2 of the four carb breathers to your air box as these have been known to suck water into the carb when doing a submerged start.

There are a number of threads expounding the virtue (or not) of above and more. Do a search on 'breather' > 1 year and you will likely get more than you need.

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  • DirtDobber

Posted April 22, 2004 - 04:13 AM


This is what I did to my 04 WR450. Check out this article.
DD :)

  • JVP

Posted April 22, 2004 - 09:48 AM


I did it just like the Mike HOBBS' article. It was an easy mod. It think this mod is a good idea considering how many people talk about getting their bikes wet. I bought the fitting at the Home Depot for about 50 cents. I think it is a waste of money to buy the Honda kit. :)

  • KentuckyWR

Posted April 22, 2004 - 12:07 PM


It is easy, instructions are on this forum, and it is cheap!
Do it!

  • bikefrk

Posted April 22, 2004 - 12:18 PM


Oil foam? White in nature sometimes. Say yes and my head will be clear. I am dripping white foam out of that hose after I thrash the bike hard.

It just dripped normal looking oil after last weekends ride.


  • SXP

Posted April 22, 2004 - 01:36 PM


Yes! Yes! Yes!

  • Joe_P

Posted April 22, 2004 - 03:05 PM


Thanks for the replies. For some reason doing a search on breather escaped me. The CR mod is basically the second bullet in the missile's post. Sounds like there are a few good options out there.

  • RobRantzow

Posted April 22, 2004 - 05:03 PM


I don't get much water in So.Cal. desert however we get alot of dirt so for a few bucks I put a Uni filter that fits the hose great and clamped it with a hose clamp and so far no problem with dirt.


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