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1990 XR200R; Remote Reservior Shock Rebuild Parts Availability;

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I posted this in my XR200 forum, however no one could offer me any guidance, so I am trying over here;

 

 

OK, so I am at a stopping point on my project due partsicon1.png availability which I could use some help with.

The internalicon1.png shock body looks to be fine, the bladder looks fine, so I don't need a new one of those.

I can get a new seal head from a variety of sources, as well the rubber bumper from Honda, however I can not for the life of me track down the pistonicon1.png ring, nor the o ring that goes behind it. Although the piston ring does not look to bad, seeing as the seal head was hammered pretty good, I thought it would be a good ideaicon1.png to change the piston ring as well.

I can not find a replacement for Part #52431-KA3-731 anywhereicon1.png. I have been to the Kayaba website, Race Tech, Ebay, I can not find one anywhere. Looks like Kayaba made a 40mm piston ring for the YZ80's/85's several years back, other than that, I have come up empty.

 

Specs; Piston Ring - 39.86mm / Seal Head Body 39.98 mm Piston Ring w/o uninstalling - ~ 40mm Diam / 8.13mm Tall

Anyone have any ideasicon1.png ???

Thanks Michael !!! 

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I didn't see one the correct height after some quick searching either. However there are some that are too tall so I would just cut one of those down. The factory piston bands appear to be something like a graphite impregnated teflon so you could use a razor blade / exacto knife to cut it. I would use calipers to scribe a line first and then slide the band over something like a piece of PVC pipe for a backer. If you're still a little wide hit it with some sandpaper and you should be good to go. Go slow, take your time and it should work fine. I would think the piston o rings for the taller height would work fine as long as there were for the same piston o.d. Clay

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Clay,

 

That is certainly "out of the box" thinking and I like it, however I do not feel comfortable enough to do such a job, aka, "I'm not the Guy". I do not have the tooling to tackle such a finite job. 

 

As Clint Eastwood said in Dirty Harry, "a man needs to know his limitations". 

 

Any rate, back the to shock, am I wrong in speculating that the shock head with the surrounding O ring does most of the work ???

 

If the piston ring/band is supposed to do it, I am .14mm+  out of spec compared to the shock body and oring.

 

I may have to send out to a professional tuner, given this might be out of realm. 

 

I think I could handle an oil change, but given parts availability, they probably would have a better line on replacement parts.

 

Michael  

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When you list "piston ring - 39.86" is this what you are measuring over the installed piston band? If so it does need to be changed. You should have to push the piston assembly into the shock with some force using that style band. Not a lot but you should definately have to push it in. If you don't it will allow fluid to bypass the valving stack and make the shock feel "mushy" for lack of a better term. The shocks I've worked on it appears to me the orings behind the band take a "set" and no longer push the band against the shock body (probably from heat) to keep everything sealed up more so than the band actually wearing. Clay

Edited by nuity5

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When you list "piston ring - 39.86" is this what you are measuring over the installed piston band?

 

 

Yes, I have yet to disassemble the shock piston, so potentially it could be the O rings behind the band that are shot, if so, that makes a lot more sense as the band itself does not look all that bad.

 

There is still plenty of teflon coating on the band, as I know what teflon impregnated coating looks like, given I work in a metal finishing shop. 

 

Thanks Clay, that does help !!!

 

Michael

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Buy a complete piston ?

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You can get the piston band without really damaging it if you're patient. I've done this cold but some heat from a hair dryer to get everything warm would help I'd think. Start with a very small screwdriver (has a round shaft like 1mm) get it under the band and start running it around the piston as your gradually pushing it deeper behind the band. Go slow and the band will stretch. Then you can insert a slightly larger screwdriver and repeat. Eventually you can stretch the band enough to get it off. This might take 10 min so be patient. I made some cone installation tools to get mine back on but I've put others on without one. Again be patient and gradually and slowly start pushing it over the piston at an angle giving it time to stretch. It will go over one side easier than the other so try both sides. Once you get it on just leave it for a while and it will pretty much return to size. Clay

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Well at the end of the day, I kept the original teflon ring in place and just replaced the shock seal head.

 

I saw several you tube posts on how to bleed the air out and approached from what I thought would be the most

likely place it would trap air. I put oil in the reservoir side and blew in reservoir side to force oil to the shock side

so as to bleed out any air in the long rubber line that is attached between them. 

 

I then put oil in both sides while keeping them secure in a workmate. I overfilled the shock side, then installed the shock

internals tried to bleed it and did the best I could, however with the rubber bumper is the way it is very difficult to bleed,

although I think at the end of the day I am pretty confident I got all the air out. I then secured the shock side with both

snap rings.

 

Then I overfilled the reservoir side and pushed the bladder and cover down using hand force as far as it would go in. It decided

to keep popping up slowly, so I used a socket and rubber hammer to punch down on it while I had a about a 10 second window

to put in the snap ring before it would come back up past the ring groove. It took several tries before I got it secured. 

 

I then filled with ~ 200lbs of air and it would not move at all. Pushed the schrader valve to release some pressure and everything

else felt right. 

 

Here is what I learned, or at least what I think I learned. The bladder effects the compression and the rebound is controlled by 

the fixed shaft orifices. Right now I am not sure if the compression clicker is working, but the rebound definitely is. I don't know if

it is the air in the bladder vs. nitrogen, or the Mobil 1 synthetic ATF is a factor. I can move the compression clickers all the way in

and out and don't feel any difference on compression. Rebound is very noticeable. 

 

I think this might be the downfall of using ATF vs. shock oil, as I am testing it moving it back and forth, it feels right in the morning

when it is cooler and feels sloppier when it is really hot. Typically in the valley in Northern California we have 65F mornings and 95F+ 

degree days. This could also be air vs. nitrogen effect as well, dunno. 

 

The question I have is why are my compression clickers not working, there were definitely cleaned out. Could it be the bladder, 

air vs. nitrogen ??? Any input appreciated. 

 

Thanks Michael 

 

XR_200_Shock_Internals.jpg

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Your going to really like the rebuilt shock.

Personally I think air is fine for the bladder, I have the stuff to do it either way and I can't tell any difference.

I decided on 7w shock oil, and it seems pretty good.

Not sure if you talked this over with race tech, but they could do a gold valve for you with more modern valve stack.

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No, given this was my first shock rebuild, I wanted to have a crack at it myself. 

 

One can also get the "heart transplant" from Works Shocks as well with piston and valve shims. 

 

I was somewhat stunned how many pieces were on the valve stack, which I did not touch.

 

I just put them in a zip tie in order, cleaned and reassembled.

 

Looks like a lot of thought went into it, so for the time being just letting it be. 

 

I posted the photo, so Guys could see what the internals look like, as I had not seen one anywhere posted. 

 

I will try to do a write up when I do the other one, in case anyone is interested in tackling such a job. 

 

I was also surprised how little oil is in the unit, I think if I take the spillage out of the equation, then it would be

close to 1/3 of a quart, or ~ 12oz's+, 12oz's is going to get trashed in short order and my guess should be

changed whenever you change your fork oil. 

 

Michael

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