Katoom

Member
Feb 19, 2002
35
0
This may be a dumb question, but I'll ask anyways. The case on my bike is seeping oil from the shaft the front sprocket is mounted on (I don't know the technical term). I haven't taken it apart yet, but my spare parts manual shows an o-ring behind the spacer and then a seal. Is this seal pressed in from the outside or the inside?

Thanks
 

FIBLANDER

Member
Nov 8, 2000
6
0
My 00 125 EXC has the same problem, the seal is on the outside, it just takes a little work to pop it out. I replaced both the seal and the rubber o-ring but it still weeps a little oil. My dealer told me that some just leak, nice! At least I store it in my buddies shop so it stains his floor and not mine!:p
 

Bill Hibbs

~SPONSOR~
Aug 25, 1999
537
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Yea, this is a bad design on KTM's part. You can pull the sprocket and clean the O ring pretty easily. What seems to work best is to clean the O'ring and put some ATV silicone sealant around the O'ring and the face of the sprocket and re-install. Although I think I noticed some oil on my boot during the last ride. :debil:
 

DanS

Sponsoring Member
Dec 6, 2000
203
0
Bill, I'm curious about where you have the o-ring. On my '99 300exc the o-ring goes on the counter shaft and then the bushing slides on. This places the o-ring on the end of the bushing inside the engine case. The sprocket presses directly against the bushing. Since I replaced the seal, bushing, and o-ring not a drop of oil has leaked out in over a year. Did they change the setup since '99?

I found that a spring puller works good to remove the old seal. You want to make sure the bushing is not grooved or scratched. The previous owner of my 300exc couldn't understand why it kept leaking after he replaced the seal. The bushing was groved about 1/32inch where the seal touched it.The other thing that gets people is the width of the front sprocket. The sprocket should just touch the bushing with a slight pressure. Some after market sprockets are too thin and need shims to work right. If it's too loose it will leak.
 
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Katoom

Member
Feb 19, 2002
35
0
Thanks guys, I called my shop and I'm going to pick up the seals tomorrow. Can I just tap this seal in with a dead-blow hammer or will that damage it?
 

Bill Hibbs

~SPONSOR~
Aug 25, 1999
537
0
Dan, obviously my KTM is the same as yours. The Seal/O-ring configuration are well known to leak. A little Sealant around the O ring helps. The O ring presses against the seal on the back of the Bushing just like yours. I guess I jumped ahead a little on my instructions and was taking the bushing for granted. Sorry for any confusion. :confused:
 

DanS

Sponsoring Member
Dec 6, 2000
203
0
Bill, I've only had mine for a year and have only had limited personal experience with other years or models so I didn't know if there was a difference in the o-ring placement, that's why I asked. KTM does seem to keep things much more standard through their model line than any other company which is nice.

I used a socket slightly smaller than the outside of the seal and gently tapped it in.
 

bsmith

Wise master of the mistic
LIFETIME SPONSOR
Jun 28, 2001
1,782
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I just bought a 13T sprocket for my bike and the dealer told me to make sure and Locktite that bolt(HH collar screw) when remounting the sprocket or it would seep oil.

It could be as simple as this versus the O-ring going bad.
It even shows a drop of Locktite in the picture of the spare parts manual.

Hope this helps;)
 

ktm3000

Member
Sep 14, 2000
13
0
I used to put a spacer behind my sprocket making it a little thicker. I think some aftermarket sprockets are just a tad thinner than stock and need a slight adjustment to hold them tight on the countershaft.

Otherwise, think of it as an Autoluber! :o
 

Reon

Member
Apr 11, 2000
101
1
Did they change the setup since '99?

I dont think so. The design is a old one, my '91 125 had exactly the same setup, could even interchange the parts with my '99.

Check whether the washer is grooved or or scratched. Also check the bushing for wear. I have also heard that some sprockets are thinner than stock and dont apply the correct pressure on the bushing/oring/washer and shims are required to rectify the problem.

On my old 125 I ended up replacing the washer, o-ring, bushing and seal and the problem went away for good.
 

Katoom

Member
Feb 19, 2002
35
0
Thanks for all the help guys. I put a new seal and o-ring in yesterday and it isn't leaking, so far:confused: . I'll know if it really worked after my ride tomorrow.
 

Buckholz

Member
Mar 15, 2000
396
0
Replace the metal collar at the same time you do the oring and the seal.

A thicker oring may help, too, if you have poor stacking tolerances.
 

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