Reroute breather hose?

10 replies to this topic
  • wr250rr

Posted April 14, 2003 - 03:22 PM


Somebody was telling me about mounting the breather hose into the air box. Has anybody done this or heard about this?

  • Crazythumpin

Posted April 14, 2003 - 03:32 PM


What, like the pcv valve or vent hose on a automobile? That could be an idea! :)

Less sludge build up and less pressure for the internals of the motor to work against.

Would have to work on an idea on keeping the oil in the head just incase she decides to start puking.

Has anyone tryed this mod?

  • ddialogue

Posted April 14, 2003 - 03:46 PM


Here's the link to the project WR450 at I'm planning on doing this mod this week as a lot of the water crossings here are getting deep with the spring run-off. I'm going to add a T plus some extra hose so the blow by will run down and can get fresh air from the airbox if the lower hose is under water.

hose reroute 1 hose reroute 2

  • foursmoke

Posted April 14, 2003 - 03:47 PM


I read it also but not quit sure where. The sole purpose of this mod was so that if you were in deep water and stalled and tried to restart that your submerged vent hose would not suck up any H2O. If I find it I will let you know where.

  • Superbike

Posted April 14, 2003 - 06:02 PM


Suck air that far up the hose :) That is a long suck. Is this theory or fact? Anyone get milky oil this way? Seems odd, but I guess it could? Just sounds far fetched. Can this really happen? I still like the airbox routing. ---Mike

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  • Indy_WR450

Posted April 14, 2003 - 07:33 PM


I think the carb needs its vent lines t'd and run into the airbox. The cam cover does not need routing like this. I ran in river crossings with water up just below the number plate air intake slot. For longer crossings you have to seal the side of the airbox cover. It will suck in some water. The vent is there to keep from blowing the valve cover off the bike.

  • endurodog

Posted April 15, 2003 - 03:25 AM


You don't really need to T the vent hoses. This is a through back to "back in the day" when there were only 2 vent hoses comeing off the carb. The new carbs have 4 vent hoses coming off the carb, they are T'd in the carb. Just take 2, 1 from each side, and run them to the airbox.

  • Junior_Vet

Posted April 15, 2003 - 06:01 PM


I just ran my breather hose between the motor mount brackets on the head, above the carb, and behind the top edge of the air box cover on the left side. I just took off the seat and pushed it in there. I did 2 motos on the weekend and I don't see any oil residue inside the cover at all.
I say this because the hose is higher, it is out of sight and can be moved back if desired since no drilling of the air box is required. Just what I did. :)

  • Indy_WR450

Posted April 15, 2003 - 06:07 PM


I would be careful with getting water in the engine. On some deep crossings I have to kill the engine and walk it across or suck water in the engine (water at the top of the seat). If your hose is higher than the valve cover it is easy for water to run straight in and fill the engine.

  • Junior_Vet

Posted April 16, 2003 - 03:55 AM


Wow that is deep! :) With water as high as the seat, doesn't the airbox fill up and ruin the air filter? or the exhaust pipe provide a way to fill up the engine? :D
If I can't see the bottom, I'm not riding in.
I understand your thinking on the breather hose though. If it is pointed down then it will keep the water out (unless suction is applied).

  • Indy_WR450

Posted April 16, 2003 - 06:24 AM


Yeah you really dont want to suck water up the engine through the intake. You never know how deep it is in some spots and you need to be prepared to kill the engine. It can take 2 people to get it across in real deep spots. when I get there I raise the front end up on a hill or bank and drain the air box and squeeze the water out of the filter. Oil remains I use Silkolene and it is super tacky. The filter will still be damp but that amount of water will not be a problem. It is better to get your ass wet than to have to deal with water in your oil. :)


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