98 KDX220 Fork Seal Replacement

[txst]

I just picked up a 98 KDX220 and stumbled upon this great forum.

This is my first post, so be gentle.

My forks are leaking and I did a search but have some questions before I tackle the seal replacement. I have only replaced seals once before on an old street bike.

1) Do I have to adjust the damping screw at the bottom of the fork either fully clockwise or counter clockwise before I attempt to remove the 14mm hex bolt?
2) I heard of people having issues with that bottom bolt just spinning and recommended a tool similar to the FRP Dampener Rod holder that has a hollow tube with a 27mm nut on the end. Looking at the parts diagram, I don't see what that nut fits into.
3) I am also going to replace the bushings while I am in there. Any other tricks that would make this easier or how to videos?

Thanks in advance!

[KDXGarage]

Welcome to kdxrider.net. Thanks for joining AND participating.

1) Do I have to adjust the damping screw at the bottom of the fork either fully clockwise or counter clockwise before I attempt to remove the 14mm hex bolt?

No.

2) I heard of people having issues with that bottom bolt just spinning and recommended a tool similar to the FRP Dampener Rod holder that has a hollow tube with a 27mm nut on the end. Looking at the parts diagram, I don't see what that nut fits into.

It fits into an internal hex, 27 mm. The cartridge is held in place by the tool. The base valve assembly (14 mm hex at the bottom) fastens into the bottom of the cartridge. One holds the cartridge still and loosens or tightens the base valve assembly.

3) I am also going to replace the bushings while I am in there. Any other tricks that would make this easier or how to videos?

One can usually get away without the tool when taking the base valve out. Compressing the fork tube puts spring pressure on the cartridge to keep it from spinning. Once it is apart, you can make a home made tool to hold it steady for reassembly if you don't want to buy the correct tool.

Let the air out of the forks before working on them.

Pour boiling water over the seal area before disassembly (or be gentle with a torch). It makes it easier to slide the tubes apart.

Don't forget to remove the circlip in the seal area.

If you don't want to spend the money on a real seal driver, read up on PVC home made seal drivers.

5 weight oil.

Read up on proper spring rates for the forks.

If you try the "shim mod", PLEASE read up on flat filing the end of the shaft. It is peened over and SHOULD be filed down before removing the nut. There have been a fair amount of threads on people destroying the base valve asembly. It is hollow aluminum. It doesn't take much heavy handedness to destroy it.

[KDXGarage]

Here's a picture I took of some 1996 forks I was working on 15 years ago.

1996KDX200Forks.jpg (49.28 KiB) Viewed 2083 times

[txst]

Wow - thank you so much for the help! I see now where the 27mm hex goes in. It looks like there is a chance of it unscrewing from the rod just as much as the chance of the base valve unscrewing from the rod during disassembly. I will use an impact gun, so hopefully it will break free easily.

I have access to a 43mm seal driver, so that will help me drive the bushing and seal in.

Thanks for the tip on heating the seal area - that's a great idea.

[KDXGarage]

The damping rod sticks out above the hex, so the 27 mm hex portion is on the end of a hollow pipe. It has to be hollow to fit over the rod.

Be careful with the impact gun. The Loctite of the base valve assembly is not as strong as the Loctite for the seal head (27 mm hex area). There is a danger of damaging the o-rings on the base valve. Hand tools are all that is needed.

A torch on a painted area is not something I am quick to rush into it. The boiling water can not be over 212 degrees F obviously, so it is not 300 or 400 like a flame (whatever it is).

Whacking them apart usually damages the bushings unless the outer tube is heated up to expand and make it easier to separate. If one is NOT replacing the bushings and wanting to separate the tubes, it is very important.

[txst]

I am going to replace the bushings, but will use the heating technique to make it easier.

Thanks for the advice on the impact - I don't want to damage anything that will keep me from being able to knock this out in a few hours because I have to order more parts.

Again, I really appreciate your help.

[KDXGarage]

You're welcome.

The people using an impact are trying to keep from having to buy or make a tool. I have done several with the proper tools and hand force.

Let the air out, take the cap off and pour out the old oil. Pump the tube a few times to get more oil out of the lower tube and cartridge. After that, put the cap on. Flip it upside down. With a helper or not, compress it down, then turn it with a breaker bar and hex key socket. Putting the axle in as a grab bar may help.

Be careful! Don't let it slip, and as always, wear safety glasses.