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Countershaft Sprocket Shaft Seal

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My 07 WR250 started leaking oil from what appears to be the countershaft sprocket shaft seal. I didn't see anything about changing specifically the seal in the manual. I did a search and it looks like its an easy fix and the cases don't have to be split. However, I couldn't find anything pertaining to WRs. I'd certainly appreciate an explanation on how to replace the seal before I end up ruining something internal. Thanks guys

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Pretty simple, remove the sprocket, the little backing plate that bolts to the motor needs to be removed, then you can pry out the seal with something sharp. Nothing to worry about.

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Are you sure it's not oil getting thrown off the chain? Sometimes that is mistaken for a bad seal. When the chain goes around a tight radius at speed, the oil gets thrown off by the chain. I think there is also an o-ring on the shaft with underneath a sleeve that runs in the countershaft seal. If so, that should be replaced too.

-Toby

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u can also screw two drywall screws in it at opposite side and then pull on them with pliers. only screw them in a little bit.

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Looks like I'm going to try replacing the countershaft seal and o-ring for my WR250R soon.

I had the master link back out and it cut a groove in the case behind the front sprocket.  After fixing that, I noticed a leak that I was worried was coming through the groove in the case.  Further inspection shows that groove is still tight but the torque on the sprocket seems to have messed up the seal around the countershaft.

 

So, now I'll try to replace the countershaft seal and o-ring.  I appreciate the above help given to 07wr250 but wouldn't mind further details.  Does anyone know about a how-to video or some more complete step-by-step instructions.  I'll give it a go with just what I know now but would love more details if they are available.

 

I have 41,000 winter commuting miles on my WR250R so far and hope to get a few more winters out of her before replacing.

Valves were great at 30,000 miles.  Had to slightly adjust the exhaust valves but they were close enough to leave them alone had I not been in there anyway.

I'll check them again at 50,000 and report in on how they are doing (if the bike makes it there).

 

Later,

Kent Larson in Minnesota

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I've fixed this a few times by running a feeler gauge around the seal. Never had to change one yet

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If anyone has done this lately, please give me some advice here.  

 

After you remove the sprocket, should the washer behind the snap ring be loose in there, or should it be pretty snug?  Mine seems like, there is a lot of space between the seal and the snap ring.  The washer tends to rattle around, so I put an o-ring between the seal and the washer, not as a seal, but as a spacer to keep the washer snug against the snap ring.  otherwise I'm concerned that the washer will be able to jam itself inside the snap ring on an angle.  

 

Thoughts?  Profound statements?  

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