Fork leak & Reducing travel

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terminatr
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Fork leak & Reducing travel

Post by terminatr »

Hi. The fork seal is seeping oil. I guess I need to tear it down and replace the fork seal. While I'm at it, I want to add spacers inside the fork to lower the front of the bike by 1.5". Right now, I have the forks raised on the triple clamp by .7", but I want more. Could someone point me to "how-to"s on replacing the fork seal and adding spacers to limit travel/lower the fork? Thanks. :boogie:
2001 KDX220
terminatr
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Fork leak & Reducing travel

Post by terminatr »

Oh never mind about the oil seal. I found videos for dummies on youtube.

What material should I use for lowering spacers on the fork?

Is it okay to buy aftermarket seals and bushings?
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gregp
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Fork leak & Reducing travel

Post by gregp »

What year is your KDX? If you have a 1995 or newer "H" series, you will have to disassemble the damper cartridge to insert the spacer - something I have not been able to do. If you have an older model, with a damper rod, the spacer needs to go onto the rod, from the bottom. This is easy to do, and I have made lowering spacers from either aluminum, or UHMW polyethylene plastic. A 1" spacer is quite significant, and you must keep in mind that the spring will now be too long, and you may have to cut some of it off (unless you are Hercules, and you can get the fork cap started without cross threading it).

This raises an interesting question for me: Can anybody show or tell me how to get an "H" series fork cartridge apart? I have seen photos of them disassembled, but when I inspected them, I could not see any way for them to come apart.... I have had other cartridges apart, and they usually have a threaded portion (cap) that unscrews from the body. I did not see anything like this on the KDX cartridges.
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1999 Ninja 250 (Daughter's)
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Fork leak & Reducing travel

Post by gregp »

BTW - I have used aftermarket fork seals without any issues. You will need to build or buy an installation tool to get the new seals in, though. I used a piece of 1 1/2" PVC pipe, and bored it out to just over 43mm. Without a tool like this, getting the upper bushing, and the new seal to seat will be very difficult. I recently rebuilt my forks with a Pro-X rebuild kit ($38) that came with new upper and lower bushings, assorted o-rings, and new seal clips. One recommendation I have for you is to install the pieces in steps. Do not try to pound in the upper bushing, the steel washer, the seal, and the wiper as an assembly! Use your fork seal tool to install the upper bushing first - using the steel washer to prevent it from being damaged by the installation tool. Then install the seal, then the wiper, then the clip.
Your installation tool should have an ID of just over 43mm, and wall thickness of about 3/16". The ends should be faced off square. The tool I made is about 6" long, and it works beautifully.
2004 Dual Sported KDX200
1999 Ninja 250 (Daughter's)
1996 DR 650 (stock, mostly street use)
terminatr
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Fork leak & Reducing travel

Post by terminatr »

I have a 2001, so it's an H.

According to the shop manual, the cartridge cylinder unit thing is removed by unscrewing the bottom of the lower leg. A special tool is needed to keep the cartridge thingy from spinning while it's being unscrewed.


Image
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gregp
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Fork leak & Reducing travel

Post by gregp »

That picture is not very detailed, and it shows only the outer tube of the damping cartridge. Yes, the base valve (#49116) screws into the bottom of the outer damper cartridge tube (#44023), but the inner portion of the damper cartridge (not shown) screws into the fork tube cap (#44029).
I have been able to remove the base valve by leaving the cap on tight, and turning the fork upside down, and compressing the entire assembly while using an electric impact wrench to remove the base valve. The cap can then be removed from the tube, unscrewed from the male portion of the damper cartridge assembly, and the spring can then be removed.
The problem that I see for you is that the spacer that you will need to fabricate will need to be placed inside of the damper cartridge, on top of the piston that is attached to the male portion of the cartridge (to prevent it from fully extending - thus reducing travel). This will require you to disassemble the damper cartridge, and, like I said, I have not been able to get them apart... Looking at that diagram, it looks like the male portion slides right out the bottom of the female portion, but IIRC, something prevented me from being able to do that...
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Post by KDXGarage »

You will need a vice and some cartridge clamps. I bought my clamps from Race Tech. You will also need a tool to turn the cartridge seal head, as you will be using it as a wrench. There is thread locker on the threads, holding it together. Wrap the area in paper towels, then give it light taps or lightly heat the area with heat (pouring boiling water over it may do the trick). There is a bushing inside there. If you have it apart, you may want to go ahead and replace those. I have bought them from Race Tech. I don't know who else sells them.

I hope all this makes sense.

Here is a picture of a 1995 - 2006 KDX200/KDX220R fork I disassembled for a member of this forum.

Image
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Fork leak & Reducing travel

Post by Frysk »

About the leaking seal
I've bought this of ebay
http://www.ebay.com/itm/SEALMATE-TOOL-T ... ca&vxp=mtr

Didn't thought it realy would work but for 5 bucks I wanted to try it.. already fixed my left seal and 2 seals of some mopeds here in the area.. its just a bit of dirt between the seal and fork so replacing the seal is just throwing away money.
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Fork leak & Reducing travel

Post by gregp »

Excellent! Thank You, Jason! I guess that I just did not try hard enough... I will machine my own cartridge clamp, and get them apart the next time I am in there... I wanted to see what could be done to increase rebound damping a bit...
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Post by KDXGarage »

You are welcome. The rebound damping is the old reverse bend style (or whatever it is called - it's late for me :grin: )

Maybe it is inverse bend. I think the shims are on racingsuspensionproducts.com (or used to be), if I am remembering correctly.
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terminatr
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Fork leak & Reducing travel

Post by terminatr »

I went to a local shop. And the gal there said she would charge $100 to lower the fork internally. That seems like a great deal to me. Cheaper than buying all the special tools.
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gregp
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Fork leak & Reducing travel

Post by gregp »

Yes, that sounds like a deal. With all of the dis-assembly required, and the machining of a custom spacer to fit inside of the damper cartridge, and the cutting of the spring (as well as grinding/flattening the end), re-assembly, and adding new oil - I'd say it is a heck of a deal. If all they do is cut the spring, or slide the tubes up in the clamps, you will have been robbed.
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terminatr
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Fork leak & Reducing travel

Post by terminatr »

Is there a formula to calculate the amount of spring to cut?

The fork spring feels too soft in the stock configuration. After I put 1.5" spacers in the fork, how much of the spring should be cut off to stiffen it up?

I weight 150# without gear after a big breakfast.
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Fork leak & Reducing travel

Post by gregp »

I am unaware of any "formula", and I usually just use a trial and error method. Hint: You can always cut more off, but you can not add on.
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Post by KDXGarage »

I guess the shop is JUST installing spacers and not working on the springs??

If so, you will just need to cut the metal tube preload spacers, not the spring. I doubt even the stock springs will be stiff enough for you.
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Fork leak & Reducing travel

Post by turner »

hey Gregp, how did you make the seal eating tool? do you have a lathe?
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Post by turner »

gregp wrote:BTW - I have used aftermarket fork seals without any issues. You will need to build or buy an installation tool to get the new seals in, though. I used a piece of 1 1/2" PVC pipe, and bored it out to just over 43mm. Without a tool like this, getting the upper bushing, and the new seal to seat will be very difficult. I recently rebuilt my forks with a Pro-X rebuild kit ($38) that came with new upper and lower bushings, assorted o-rings, and new seal clips. One recommendation I have for you is to install the pieces in steps. Do not try to pound in the upper bushing, the steel washer, the seal, and the wiper as an assembly! Use your fork seal tool to install the upper bushing first - using the steel washer to prevent it from being damaged by the installation tool. Then install the seal, then the wiper, then the clip.
Your installation tool should have an ID of just over 43mm, and wall thickness of about 3/16". The ends should be faced off square. The tool I made is about 6" long, and it works beautifully.
did you make this with a lathe?
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Fork leak & Reducing travel

Post by gregp »

Turner - yes. I have access to a lathe. Without one, I could not find a piece of stock sized pipe that would do the job. I looked at PVC, Type M and Type L copper, EMT, and other stock pipe that I have in my shop, but could not find a suitable piece, so I had to turn a piece down.
The job *can* be done without a special tool, though. If you lay the new seal in place, lay the steel washer on top of it, and gently tap the washer with a small punch, you can "walk" the new seal into place...
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Fork leak & Reducing travel

Post by gregp »

BTW - If you (or someone else) just cuts the pre-load spacer, and you install the stock springs into the shortened forks, you will end up with shortened forks that are way too soft - They will blow right through the reduced amount of travel, and bottom out hard over small bumps.
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Post by KDXGarage »

The rate of the fork spring won't change, it is still butter soft. :grin:
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