'00 YZ426 lower fork slider

I just pulled my forks apart to replace the seals and wipers. On the right lower leg about midway down the slider where it is supposed to be shinny silver it has a patch about 1-1.5" wide and 3-4" long where the silver looks like its rubbed off. It's kind of a black color. Almost looks like it has been heat treated (only analogy I can think of). It's still kind of shinny, but not bright silver, almost like a gun metal grey.

1) Do you know what it is and what may have caused this (blown for seal, bushing rubbing, etc.)?

2) Will it cause a problem or is it a major problem? If so how do I get it fixed?

I have a couple of theories as to why this happened, but wanted to get everyone else's perspective, opinion, solution, etc.


John E. Walker


Are you saying your inner fork tube has a wear spot on it? I would think this is due to the inner tube being bent. How are the bushings? Is there still teflon on them?



I noticed the same kind of surface finish on one of my forks. It looks as if the chrome has been rubbed off on a couple small spots. I would guess that as long as you can not feel the difference (with your finger nail) it would not be a big deal. Fork seal life is what I would worry about if the surface starts to get worse. If the surface starts to get worse or you can feel scratches or imperfections, I am going to worry about it then. I am sure it would not be a huge deal to take them to an industrial chrome plater and have them redone, but I am going to wait until that point to do so. Keep us informed on the progress of the "spotting fork tube". I will do the same.

My guess is that Yahmaha (or more specifically Kayaba (sp?)) Did a bad chrome job on some forks, they could have had some contamination in those spots and this is why it rubbed off..... I would hate to think there was something wrong inside the fork that would rub right through a hard chrome finish..... Usually this type of chrome is extremely hard and most definatly not be rubbed off by the fork seal.....

For $608 (hlsm web site Price) I sure as hell hope I would not have to replace the fork!

I have a 00 YZ426, picked it up in May of last year. It would be interesting to find out how common this symptom is..... On other bikes with the same forks. I changed my fork fluid mid season last year, did not see anything funny when I took the forks apart. Does anyone think that having the settings being close to maxed out would have any effect on this? I would not think so but I am no expert.

Hope this helps


[This message has been edited by Tim (edited 04-06-2001).]


That doesn't sound good.

If you have lost chrome, you'll need to either get them re-done or get a new fork tube. You can maybe polish it down, but it's just a matter of time before it starts to eat into the teflon, (if it hasn't already).

Do make sure this is the case, and that it's not some sort of thin build-up, or some weird hot spot.

You may also want to consider a titanium nitride coating, although this has dropped in popularity on the dirt bike sceene. Let me know if you want to go that way and I'll give ya some tips and contacts.

And you may want to call Yamaha or KYB and have a little chat with them. They really can't deny something like this. Let me know if you need their numbers.


A little more info on the problem. My last race (this past weekend) was another mud bath. The bike was raced for over 3 hours in these conditions, with it getting stuck (burried) at least twice. After I got home both fork seals were leaking bad.

Dave, I think your onto something there. My thinking is this: when I pulled the forks apart the seals were blown so bad that mud had worked its way up past the seals into the bushings. There was mud even packed under the inner bushing. I talked to Rob Mann at GP-Racing (he did my suspension) and the best theory we can come up with is maybe mud got packed in between the slider and the seal and caused a hot spot. As I stated in my first post it looks like it has been heat treated. The chrome is not worn or flaking off, just discolored in that area. The best I can tell, with my hands and fingers, the surface of the slider is not damaged in any way. So going with that theory, is there a fix? Or could this lead to possibly more damage?

I am very interested in the titanium nitride coating. But with the slider being discolored will it cover it up, or will the discoloration show through? Let me know about the info/contacts you have. The only one I know is FC and I think they charge about $250.

After my race this weekend we have a good break in our schedule and I'm sending my suspension back to Rob to get it hard anodized, so this would be a good time.

On another note, I don't remember if it was you or Scott, but I got the bottoming cones when Rob did my suspension, and they are MAGIC. I won't ride another bike without them.

Thanks for the help.


John E. Walker



Well…that does sound like quite the mud bath. Perhaps some fork booties are in order.

In either event, it sounds like the forks are going to have to come completely apart. A great time to inspect everything.

As for the hot spot, it really depends on how far into the chrome layer the burn is. You may be able to polish it off, or at lease the edge portions where the heat was not as dramatic.

And what are you going to get hard-anodized?

As for titanium nitride, I don't see the factory teams doing this anymore. I've talked to a few shops and some feel that it's too complicated and can weaken the tube, which could be a problem for Supercross and FMX. However, I still had mine done just for the experimentation of it.

The best place for this is TiGold back in Kennebunk Maine. Check out www.tigold.com or call them at 207-985-3232. They have done plenty of moto tubes and are very good at it. However, if they experience any contamination in the chamber, it can cause a less than perfect job. This happened once to a set of some road bike tubes I sent in – fortunately not in an area that the seal rode on. I pay $50 per tube, (yes, that’s the price you get when you don’t deal with so many middle-men).

You will, however, need to remove what's call the "castings" at the bottom of the forks before you send them in. These are the aluminum pieces that are screwed on the bottom of the lower tubes. Not an easy job. You'll need to remove the set screws (which are partially peened in place) and then with a lot of heat and force, you can unscrew them.

If you need to talk to KYB, you can reach them at 562-799-3862, (California). Ask for John.

Let me know how it goes.


And what are you going to get hard-anodized?

The shock body, cartridge rods and tubes. What are your thoughts on this?

EMA, that was me who turned y'all onto the bottoming cones.

I have seen the type of marks you refer to. I'm not looking at your tubes, but if the chrome is not damaged, you can just polish the tubes and run them. IMO, the dark marks are deposits from the bushings. If you really need a tube, I may have a spare one.

It sounds like you may have some internal damage from the mud. You need to do a 100% teardown.

I don't recommend anodizing those close tolerance parts, since they are already anodized. Good luck.

I don't know if I really "need" a tube yet, but am interested anyway. I like things to be "right" and a new tube would help me sleep better at night. I think my wife calls it being anal. :)

Everything is back together and I didn't notice any damage, but I'm a novice at this. Either way it's going back to Rob to get a little fine tuning done on the valving. That is the part I really want to learn.


Scott's right, you don't need to anodize that stuff unless it is damaged and needs to be redone. And the tubes are steel, so there is no anodizing process.

And 100% tear down means just that. This includes your valve stacks, so be prepared to spend some time with them or make sure the local shop really understands what needs to be done here.

Best of luck and let us know how it goes.


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