Breather hose mods?!

11 replies to this topic
  • boer

Posted October 25, 2006 - 08:15 PM


So I have doen some searches on the topic and my understanding so far is that the older WR's had their crankcase breathers simply routed done the side of the bike. :banana: Many guys modified this by rerouting the hose to the airbox which is now a standard done by Yamaha on the newer WR's.:mad:

I have a 06 WR450 and am concerned about the breather being firstly on the bottom of the airbox and secondly open to atmosphere without any filtration. :D I have seen some posts about rerouting the brether to the capped off AIS fitting on the inlet side of the airfilter, however I have my doubts about the routing and the affects of vacuum on the inlet.:ride:

What have the most of you done about this breather. :mad: Could one install a small inline filter to prevent dirt from being sucked from airbox into camcover etc.:worthy: Has anybody done this?

What about the carb breather hoses that run to the bottom of the bike? Do these suck or blow as they are permantly in the dirt at the bottom of the bike:thumbsdn:

Am I just paranoid or can some simple mods be done?:foul: Look forward to your opinions? :mad:

  • clark4131

Posted October 25, 2006 - 11:05 PM


There is such a small differential between the atmosphere and the pressure/vacuum that the crankcase generates that worrying about it is, as you said, just paranoia. A little oil may seep into your airbox, but that is what the little drain pouch is for on the lower side of the airbox, along with any water that gets in should you do a deep crossing. On the '06, your effort is better spent worrying about whether or not your valve caps are on tight enough...SC

  • boer

Posted October 25, 2006 - 11:37 PM


Thanks Clark4131,

No water here in the desert...I am still concerned that the dirt in the airbox can make it's way to the camcover/crankcase through the breather :mad:

Excuse the stupidity, which valve caps do you mean?

  • waynus

Posted October 26, 2006 - 02:44 AM


I reckon at the bottom of the airbox is the best place for it. There should I think be a negative pressure in the airbox meaning that it will suck rather than blow. Cars over the years I have noticed also have theirs routed to the aircleaner housing but on the outside of the airfilter.

  • clark4131

Posted October 26, 2006 - 05:14 AM


... which valve caps do you mean?

The ones on your tires :mad:...SC

  • Alley Cat

Posted October 26, 2006 - 07:34 AM


The ones on your tires :mad:...SC

:mad: Too funny! But true! :mad:

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  • pjriss

Posted October 26, 2006 - 08:52 AM


Take your pick of these filters:

I have one on the end of my hose. My crankcase breather hose that is..:mad:

  • boer

Posted October 27, 2006 - 04:44 AM


The ones on your tires :mad:...SC

:mad: Thanks Clark, in other words no extra mods are required, it is fine just as it is? :mad:

  • A-ron

Posted October 27, 2006 - 07:37 PM


The ones on your tires :mad:...SC

I'm cracking up...that is way funny!

  • Nashty

Posted October 31, 2006 - 04:19 AM


I've SuperMoto'd my WR426 so I had to add a catch can. I made one out of sheetmetal and it replaces the hose clamp/guide that routes the hoses over the back of the motor (where the starter goes on the 450's). All the carb vents dump into it, the puke tank dumps there and the vent hose has been re-routed to the other side of the motor, goes down the external oil line and into the new catch tank. I have a small breather on the top of the new catch tank to let it all air out. I put a 1/8" NPT bung on the end of it and plug it for a race and then just put a nipple on it for regular street or backyard riding.

  • C-P

Posted November 02, 2006 - 08:20 PM


The breather hose on my '98 was rerouted over the airbox by previous owner...oil puked out all over in the airbox, so I moved it back. Is there a valve in there somewhere I need to replace?

  • Alley Cat

Posted November 03, 2006 - 02:04 AM


The breather hose on my '98 was rerouted over the airbox by previous owner...oil puked out all over in the airbox, so I moved it back. Is there a valve in there somewhere I need to replace?

No, but you can put a t piece in there with a blanked off hose piece. Just empty it now and again.


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