Another WR glitch ??

A buddy of mine just bought an '04 WR 450. The bike has 150 miles on the odo. Last week he took the bike to the desert, and the bike ran flawless. Right before heading back to the truck, his riding buddy informs him that he has oil dripping off of his boot. When he looks down, aside from an oil drenched boot, he finds that the two half-moon shaped rubber gaskets have blown out of the head, and are allowing the complete draining of the engine oil. He had a heck of a time getting the rubbers back in so he could limp the bike to the truck. He didn't know how much oil he lost, but it didn't sound like any permanent damage occurred. Has anybody had this problem, and what causes it? I thought that it might have been a product of a plugged/pinched breather tube, but it doesn't appear that this is the case, as the tube seems to be fine. Thanks, rekless :thumbsup:

There should be half moon magnesium spacers in the rubber. Check that they are there, otherwise I think its almost impossible for them to come out, unless the breather were blocked. Are you sure he didn't over fill with oil? :thumbsup:

I'm positive he didn't overfill, in fact he didn't add any oil due to the fact that he had only ridden 150 miles and the oil level was fine. The funny thing is that when he took it into the local dealer, they told him that since it was two weeks out of warranty, they wouldn't be doing the repair for free. I thought that was bull$#!+. They did say that they would call YAMAHA and maybe they would agree toake care of it. BTW, the dealer has had the bike for nearly three weeks. It's getting ridiculous. Thanks yall, rekless.

I finally got to register with TT. I took the bike to Vegas and went riding. About two miles in to the desert I found that the two half moon shaped parts on the valve cover gasket were sticking straight out. The magnisium spacers were still embedded in the gasket and I had lost some oil. Those things don't just push back in. I had to cut them away and reinsert them. Rekles and I checked the breather tub and found no kinks or obstructions in the hose. The only mods I have done to the bike is a JD kit and cut the bs throttle stop. O and changed the handle bars. Maybe it was the bars.

it happened to my buddies '04 the first time he rode it. the bike "popped" and blew one of the plugs out. he was so freaked by the noise he looked down at the bike while still moving and hit a tree. 36 miles on the bike and a smashed radiator. the dealer couldn't find anything wrong.

yamahas (and most four strokes) will back fire when the pilot jetting is a little lean. how this would build that much pressure in the crankcase is beyond me. all i know is that it has not happened again. we did richen his jetting, though. in the winter(when it happened)we went to a 48 pilot jet. now that it's warm, we went back to the 45. we turned out the pilot fuel screw till it no longer has the small back fires when you get off the throttle.

Which dealer are you taking it to? Wilsons or Clawsons? I have a hell of time getting Wilsons to do a darn thing, and when they do anything it is usually slow and wrong. I would call Yamaha myself and get them to do it for free. Sorry I don't have any explanations of why it happened.

weird, sounds like a defect to me on that bike only. I've got 180 miles on my 04 WR450F of hard desert riding and not one single problem. Love my WR to death!

it happened on my YZ. does it happen when ur really railin on it? its got to be the breather tube. if its not kinked, could it be clogged?

when it happened to me, it was only when i was really gettin on it and the pressure was building up. and i put it back together because the breather didnt look kinked too bad, it wasnt totally kinked but it was a little, after it blew out again i had to make a different breather tube and it worked fine since..


What size is the stock pilot jet. We put the JD kit in since I have had good luck with it. Now that you mention it, it does "POP" on deceleration...maybe that is what caused it. Verde...let's try the pilot jet. I always thought that the popping was the result of a rich condition on deceleration. Is it actually too lean? Also...WR372, we took it to Clawson's and they have always been pretty good, I just could't figure out why they would not fix it with only 150 miles on the odo. Thanks guys for and Verde will keep you posted on the end result. :devil::thumbsup::awww:

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