Issue with fork seals

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5/4/2018 9:36 AM
Edited Date/Time: 5/4/2018 9:38 AM

Howdy all.

Over the past year, I've been restoring a 1991 KX250 for my father, as he had one way back in the day. The disc side fork seal was leaking, so I tore both forks apart and replaced the seals, as it was making a heck of a mess.

Bought the seals and correct driver (43mm).

Put it back together and....

The disc side fork seal is still leaking. Neither he nor I haven't ridden it at all, and I walked out into the garage to a fairly large puddle of oil on the cardboard I had laid down as a security measure.


What are issues that could cause a brand new fork seal with zero rides to leak? Is there a good way to make sure the fork leg isn't ever so slightly bent? Could bad bushings cause the fork to sit unevenly and weep oil?

Is there an easy way to check wheel alignment to make sure it's not binding the fork?

Thanks!

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5/4/2018 9:40 AM

Possibilities:
-the fork seal was put in upside down
-the lower leg has a big gouge/mark in it somewhere
-the seal was damaged when installing it (did you use something to protect it from the sharp edge when slipping over the fork leg?)

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5/4/2018 9:44 AM
Edited Date/Time: 5/4/2018 9:51 AM

seth505 wrote:

Possibilities:
-the fork seal was put in upside down
-the lower leg has a big gouge/mark in it somewhere
-the seal was damaged ...more

-the fork seal was put in upside down

The fork seals have a bit of a ridge in them that the dust seal locks into, not to mention - there's the weird retainer clip that holds the seal itself in. I can check this sometime this weekend

-the lower leg has a big gouge/mark in it somewhere

I actually checked this during the install of the seals. I did not see any marks whatsoever on the leg.

-the seal was damaged when installing it (did you use something to protect it from the sharp edge when slipping over the fork leg?)

I used the wrapper of the seals to protect the seal itself when sliding it over the end of the fork.

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5/4/2018 11:26 AM

They make a product called a “bullet” that slips over the top of the lower leg to protect the seals during install. Its basically a rubber/plastic sleeve with a chamfer on the top. Personally ive always been lucky using the wrapper and suspension oil as lube to install mine and have never had issues.

Another possibility is a bent tube or poor quality seals. Over filling with oil might cause a leak - not sure tho.. never did it.

Also what i do on the seals is put some grease around the outside, where they contact the upper tube. I feel this will help prevent leaks.

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5/4/2018 12:49 PM

Yes worn bushings will allow the fork seals to leak. They should always be replaced when new seals are installed.
The seal edges can be damaged if the correct tools are not used. Dirt in a new seal can make it leak. Scratched fork leg can cause the seals to leak.
Always install the seals on the legs prior to installing the bushings.

Paw Paw

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