'98 WR 400 Replacing Fork Seals on Vortex Modified Suspension

Hi All,

I've never changed anything with the suspension since I bought the bike from the previous owner. I have barely ridden the thing in the past few years, and I just got it back from the shop after almost a year of not really riding the bike at all. After the ride back to my house, I noticed the left fork tube was dripping oil! It did not appear to be dripping consistently but there was definitely a lot on the fork. Is this normal from sitting for a while?

I assume I need to change the fork seals, but I have a few questions. According the the previous owner; the forks were set up for a 180lb rider and set up more for street riding (supermoto). There is a vortex sticker on the suspension, so I'm assuming that's who did the work. Should I follow the service manual on seal change and fluid level etc, or will it be different for my "modified" suspension? Is there anything beside the seals/bushings I need to replace? Is there a recommended brand, or is something like this: ebay kit

Are there any modifications I should make that have been discovered in the last 13 years that improve the way that the suspension works?

Any suggestions appreciated.


EDIT: After further looking into this, it doesn't look like Vortex does suspension at all. Either way that doesn't make much difference I wouldn't think.

Edited by nnamssorxela
additional info

i just re did mine last night... it's not that hard and shouldn't matter if it was stock or modified to begin with.

let me know if you needs the steps on how to do it

Thanks for the help!

I'll probably read through the manual and see what it says. I've heard to can drive on the new seals with the old seal and fork tube, or use a piece of plastic pipe. Trying to avoid any special tools.

Did you just order a generic seal and bushing kit like the only I linked? Anything else I should replace while I'm in there?

i did the MSR bushings and Pivot Works dust seals/fork seals, the bushings all looked good in mine but i replaced them anyways. We just did the 2 larger ones on top and the new clip, my buddy wasn't sure about taking all the small stuff apart so we left it together. we used a punch to drive the seals in with a little lube, worked well

Thanks for the tips. I'll probably be ordering those parts the next few days.

As far as oil goes, without opening a can of worms, is one oil better than another in terms of street use versus off road? I'll probably pick some up at my local shop but I was curious to hear what the other members on here think.

I've been having the worst trouble with these. What should have been a days work has turned into almost a month, which seems to be the trend with everything I work on with this bike.

So I was having a difficult time separating the inner and outer tubes. I tried the "slide hammer" method but thought something else was holding them together. I talked to my local shop and he said the base valve MUST come out or I will damage the forks. I showed him the manual and some youtube vids that said otherwise and he said it didn't matter...the base valve needed to come out. So I track down a giant 14mm allen wrench and break those suckers loose. They spun out a little then stopped. Then I found out that this happens when the base valve begins to unthread, then the inner portion just spins around and must be held with a special tool.

I decided screw it, I'll just pull them apart like everyone said (slide hammer), and just use a little more force. Naturally it worked first try but I still had to deal with the base valves. I then decided I would just screw the base valves back in and be done with it.

Of course it wasn't that simple. The inner portion still spun around when trying to tighten the base valve, and plastic spring guide makes it so the inner portion couldn't be held with the special tool (PVC with notches). No worries, I'll just undo the lock nut and pull it off....and again....it wasn't that simple. The nut on one fork was stuck, and the nut on the other would begin to un-thread, and then stop before the threads came out of the bottom, so I assume the very last thread on the nut is being stubborn. I was able to knock the stuck nut free by whacking the wrench swiftly while holding the top part of the threads tightly(OUCH). I tried this method on the other with no luck. I even wrapped the rod in a cut up inner tube to get a better grip to back the nut off, but again, no such luck.

What should I do? I was thinking of getting an impact wrench to knock that nut off, but I'm worried the threads on the rod could get all messed up and cross threaded.

Now I can't even ride my bicycle to class because I cut up my inner tube.:thumbsup:

Update: The impact gun did the trick for removing and then getting the stubborn nut back on, but I am still having trouble.

The lower bushing or piston (the copper looking split teflon coated ring at the bottom), will not go in. I could hammer the snot out of it to get it in without the inner tube in there, but obviously the fork cannot be assembled in this manner.

I took it to the shop and they said it was because I bought it on ebay :busted: and that it should slide right in, but after the wrong info they gave me last time I'm hesitant to believe them.

I am skeptical because the old one I pulled out didn't slide right back in either. to humor them (and myself) I ordered one from their catalog but I am 99% sure I will have the same problem.

Is my only option to file the split/gap edges a little so it can get smaller and fit in the outer fork tube?

For the love of everything someone PLEASE help me with this.


Apparently I don't beg enough or something in my posts, or I'm too technical or boring for you guys so I'll try a new approach.

Just swung by the shop to pick up the split metal piston/sleeve/slider. WRONG ONE, no surprise there. It was 5ET-23171-L0-00 which has superseded 4SS-23171-L0-00. This part looks like the one that slides onto the UPPER part of the INNER fork tube. I am looking for the one that is a little smaller ( less than 1/2 inch high versus 3/4 inch high which is WRONG) and fits into the LOWER part of the OUTER fork tube. I've been told by several yamaha dealers and parts counters in several states that all say 5ET-23171-L0-00 (formerly 4SS-23171-L0-00) is the CORRECT part number for the slide that fits into the LOWER part of the OUTER fork tube just before the washer, oil seal, stopper ring, and dust seal.

The slide in the kit I got off ebay appears identical to the one I pulled out but now it's beat to shit from trying to drive it in and will scratch the inner tube during motion. According to the service department at my local dealer it is the WRONG one and the proper one should just slide in.

I'm tempted to take the 2nd one from the kit and file it down so that it slides in, then just buy another kit to get another slider from it?


I'm looking for anything here people.

The part you're after for a 98 WR400 looks to be a 4SS-23125-L0-00?

The bushing doesn't just drop into the fork leg, it requires a little force with the PROPER tool to seat it.

Don't be a butcher, buy or borrow the right tools to do the job.

Thanks, my service guy at my local parts place was kind enough to let me use his fork seal driver and was also the one to tell me that it wouldn't work and was not supposed to require that much force. Though he was also the one to tell me the base valve needed to be removed to separate the tubes :busted:

For snots and giggles, I went home and drove it into the outer tube myself (albeit without the proper tool and without the inner tube in the way), and I had to beat the heck out of it to have it sit fully flush, and then use a slide hammer to get the dang thing back out. I don't think that with the inner tube in there, that you would be able apply enough force on the sliding fork seal driver to push it in. Also, why is that piece $30 each when my whole kit was under $60? And then another $50 for the fork seal driver because the shop won't let me use theirs with force. I might as well part these and buy some new forks for the price I have in them.

I must be missing something here?


You asked, and I told you.

Have you double checked the correct part number, as the one I found is different from the number(s) you posted?

The service manual has all the info you need to do this job correctly.

I can't help you with parts pricing, and am not going to debate how worth while it is to invest in the proper tools you'll likely use for years to come.

I'd also bet that any $100.00 set of forks you buy will need serviced, and then you're back to square one.

Good luck.

Thank you for addressing me by my proper name.

I was not questioning you, I was just curious. I've been told by several people different things, all of which were the opposite of what you said.

I was trying to put 2 and 2 together as to why those 2 bushings were almost 100% of the cost of the entire kit which contains a lot more than just those 2 as you know. I figured maybe I was overlooking something, not complaining. I was however complaining about the total cost of this suspension rebuild being close to the cost of used suspension in good condition due, I guess to my incompetence or inability to successfully diagnose and fix my suspension. If you look back you will see in my first post that I was not familiar with suspension, hence why I am constantly second guessing and questioning all the various "solutions" to my "problem."

Yes this stuff seems simple, but when I take it to a shop and they can't figure it out either, I begin to question if I have the right parts, or if I'm following the right procedure.

And yes, I also know there is the right tool for every job, and like I mentioned earlier I was just poking fun at the frustration of spending so much on essentially nothing when I could have spent the same or even a little less to have a better end product, or at least a starting point....in my opinion.

Thank you for your input.

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