12 replies to this topic
  • Drtbykr

Posted July 22, 2004 - 02:34 AM


My WR with 540kms on it is in the shop with top end problems due to water and sandy material getting into the top end.

Do a search on the crank case, carb vent and other mods now, submarine your bike and save a huge bill. I have one coming that is going to lay my bike up my lovely new machine (used to be) for a long time. I am going to miss trail riding big time, and the payments keep coming.

Save yourself my grief and do the mods now. P.S. I never did anything all the other bikes (mostly CRF's) I was with do.

  • vantolr

Posted July 22, 2004 - 03:10 AM


do you have link to the mods.?

man, that really stinks! :thumbsup:

  • Drtbykr

Posted July 22, 2004 - 04:03 AM


Some more experienced member may have some. I use the search option and found how people have routed the crankcase breather hose into the airbox.

Also the carburetor breather hose.

Do it before your next ride.

  • montanaWR250F

Posted July 22, 2004 - 06:26 AM


This has instructions for mods that also apply to 450


  • Fryboy

Posted July 22, 2004 - 07:00 AM


The most likely cause for the top end damage would be starting your bike with the breather tube still in the water. It has been proven that water will get sucked up the breather and into the top end.

Water/mud/crap could have also gone down the exhaust settling in the headpipe and most likely entering your top end.

The only other way I could see causing this is your filter not being completely sealed and/or comprimised with the water entering the air box entering the carb then top end.

Moving the vent tubes from the carb will prevent your engine from stalling once the bike is in the water but has nothing to do with crap getting into your topend IMO.

I haven't moved my breather and I have been in water as deep as bottom of seat. Luckily I haven't dropped it in the drink yet. If you ever stall in the water, DO NOT try and start the engine if the breather is underwater.

Push the sucker to dry land. Stand the bike on its butt, to drain any water from head/tail pipe. Then take your filter off and wring that out until relatively dry. Once you get out of there kill the engine and do an oil change or 2 or 3 until no milky white is seen on dipstick and/or when you drain the oil out.


  • Mike_Hudson

Posted July 22, 2004 - 10:02 AM


The theory on moving the carb vents is that if they are down in the airbox below the carb throat and water starts to flood the airbox the vent tubes will not function, stopping the motor. I've not tested it, but I did move them! :thumbsup:

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  • 4strokeMe

Posted July 22, 2004 - 04:14 PM


How do you search for these Mods? :thumbsup:

  • Drtbykr

Posted July 29, 2004 - 09:47 AM


Total bill, approximately $850 Can. Will have the bike back this weak. Only parts required are rings and gaskets and a bearing. I'm not good enough mechanically to do this work myself (would have tried it over the winter, but I want that bike back now).
The oil screen in the inner sanctums was clogged up and the top end starved a bit. I didn't drive a block in this condition since it happened close to home. The dealer doesn't seem to have much sympathy (they have a monopoly),they said they synthetic oil I was using probably saved the top end. The cams aren't perfect but they are going back in. P.S. No water or mud in the air box carburetor.
I am going to write Yamaha and official letter explaining how I feel that the cylinder head breather hose design is not designed well for the intended use of the vehicle. I was only in about 6 inches of mud. (so were the CRF's but they have a better design I'm told). I'll try that, I'll try small claims if necessary. If it can get a letter or fix out from Yamaha and save another WR dirt biker grief it will be worth it. A stupid design if I say so myself.

Good news is the CMRC Nationals will be in Riverglade this weekend coming, and they are a piece of heaven to watch.

Go luck all guys and girls entering.

  • tigerowner_ut

Posted July 29, 2004 - 01:02 PM


Here is a link that shows the mod.


  • sabin

Posted July 30, 2004 - 11:22 PM


The 450 preather design is diffetent than the 426. I do not know how exactly, but there is no oil dropping with the 450 and THERE IS DIRTH ENTERING THE ENGINE. I never started my engine in water and when I dismounted my head cover to check valve clearances I put mu little finger in the hole where the beather goes. THERE WERE DIRTH IN THERE! So I can only guess how much ditrh actually entered the engine, but it SURE did! I routed my preather in the yamaha designed place e.g. on the top of the rubber boot between carb and filter.

  • ETP

Posted July 31, 2004 - 03:50 AM


Sorry about your problems.
I did the breather hose "tee" mods, but did not want to drill a hole my air box, so I tied the high hose ends up under the seat with a foam sock on the ends.

  • nofear14

Posted July 31, 2004 - 04:45 AM


if i get an 05 wr450 iwll i still have this problem or have they worked it out for the 05s?

  • ETP

Posted July 31, 2004 - 06:03 AM


A few years ago after a four foot crossing, my buddy's DR350 got completely water logged and my XR600 did not. I don't know if the problem should be considered a design flaw. If they start advertising these bikes as "amphibious", then maybe so.


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