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CRF450 Front Sprocket Question

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Hey guys, was removing the front sprocket off of my 05 CRF450R and as I pulled it off, a broken seal fell out from behind it...?! Never in my life did I know they had a seal behind the sprocket?? Do I have to replace this thing or what?

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The seal shouldn't be immediately behind the sprocket. Behind the sprocket is the seal collar and that rubber ring slips inside that collar but faces away from the sprocket, towards the countershaft bearing. If your seal was immediately behind the sprocket, the collar might be mounted backwards, or someone added an extra ring to seal a leak. Remove the collar, clean up the countershaft splines, grease them, grease the new rubber ring, slip the ring inside the collar (collar can't be grooved at the outer seal seating area or it will leak!, some guys turn the collar around for a quick fix to get the sealing back if collar is grooved...) and slip collar/ring assembly onto shaft with ring-side going on first.

Edited by Eddie8v
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the collar likely just came out with the sprocket. could have rusted on or enough grunge it came out with it.
if you do mount that collar backwards, with the groove facing out, that o-ring seal is junk. It gets smashed .. ensure the thin rubber ring goes inside that grove. with those 2 out of the way, the cs seal can easily be pried out of the engine case.

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the collar likely just came out with the sprocket. could have rusted on or enough grunge it came out with it.

if you do mount that collar backwards, with the groove facing out, that o-ring seal is junk. It gets smashed .. ensure the thin rubber ring goes inside that grove. with those 2 out of the way, the cs seal can easily be pried out of the engine case.

I have been fortunate and never had a leak there so no real world experience with the fix. Good to know

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Here is how I found the sprocket on the bike from previous owner...

1.jpg

 

Here is the way the manual says to face it...

2.jpg

 

Here is what I found immediatley when I removed the sprocket....

3.jpg

 

Here is when I took the collar off (a bit damaged but the collar was facing the right way, with seal inwards)

4.jpg

 

Here is what looks like some water/oil.. is this normal or does this mean theres water where it shouldnt be?

5.jpg

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The third pic, I don't know wtf that messed up rubber hose is. Looks like a carb vent hose got caught up. The 4th pic- that o-ring IS the seal but shouldn't fit inside the coller like that. Either it's stretched or the wrong coller is on the bike.

Edited by Diggla117

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Your main seal is busted, that's the broken seal you saw upon sprocket removal. Replace that main seal and the collar if the collar is grooved, and the little rubber ring seal too He had the sprocket mounted the correct way.

Edited by Eddie8v

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Not to be nagging, but just need some clearification... Eddie, is that thing a vent tube then or what? Because its not anything in the parts diagram, the large seal closest to the bearing is still seated in there, and then there is the D-ring seal that sits in the collar.. other than that there shouldnt be any other seals. And when I first asked about an O ring seal I was talking about that tube thing that is torn to pieces... not sure what you're saying, sorry about that.

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Oh, sorry, hard for me to see on my tiny Blackberry screen. Looks like a piece of carb vent hose (or a piece of fuel line?) got wrapped around in there, if the countershaft seal is ok that's cool, but be careful that hose piece could have tweaked the seal a bit and honestly, while it's apart, I would replace all 3 parts so it'll be ok for years to come. Cheap and easy to do...

Check your carb for missing/short vent hoses!

Truly amazes me the crap I have seen wrapped around in there over the years...

Edited by Eddie8v

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And what about the water in there? Should I drain my trans. oil and look at it?

I can't see water but my guess is that piece of hose held the sealing area "open" and water was allowed to enter during washing or river crossings. Yet another reason to replace all the parts. Drain the trans oil, replace all the parts, re-fill trans with ATF and hammer it for 1hr and see if all is well, the ATF will clean it all out inside. Then when warm, drain/refill trans oil 1 more time to be sure to remove all water, dirt and other contaminants. Edited by Eddie8v

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Thanks a lot for the clearification and helpfulness. New bike to me so I'm sure Ill have more questions in the future haha...

 

Will be replacing those parts and see what happens. Appreciate everything guys!

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""Edit: Sorry, I just saw Eddie covered this already""

 

I see the liquid in the last pic. Does look like water. Did you just wash the bike? I wonder if water somehow got high pressure sprayed into all that and remained trapped after the rest of the bike dried. Other then that, yes drain both sides and check for water/coolant.

Edited by mrmoto35

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mrmoto35 - I did wash the bike a few days ago and havent ran it since then. Must be the case because I just drained the oil and it is fresh and clean!

 

One last thing, any tips on getting the large seal out of there??? Dang that sucker is in there..

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