'99 XR 600 R Rear Shock Troubles

[jbehunin]

Hello all!

I am scratching my head on this one.

I needed a rebuild on my rear shock. The rear shock was spongey and springy. So I bought a new inner seal, bladder, bumper and oil and tire the shock off the bike.

The tear down was normal with no problems. The shock was cleaned and inspected. The new parts went on with no issues at all.

Re-assembly of the shock went all according to plan until it came time to charge the bladder with nitrogen.

After 180psi, the shaft was not extending as usual.

So I took the shock to my local dealer, and it's doing the same thing to him. We are all stumped on this one.

The shaft is in good shape with no nicks or bends and the oil levels were good.

Can anyone help us on this????

Thanks!!!

[bork]

Check your rebound valve adjuster knob. turn it to the 1/2 way point. I forget how many turns or clicks, I'm guessing around 12 clicks would be 1/2 way. If that doesn't work, something is wrong. Is the schrader valve working?

[jbehunin]

We have tried it at the full open to the half way point on both adjusters. I'll re-check the Schrader valve to make sure it's letting the nitrogen in the bladder, but I'm sure it is because we bleed out the nitrogen after each time....

[Adamthomas]

Do you get resistance when you try to compress the shock by hand? If the shock easily compresses, could there be an issue with your compression and rebound valving? Loctite migrating from your shock shaft nut? You certain there's no air trapped in there? Just throwing stuff out there for you.

Edited January 17, 2017 by Adamthomas

[jbehunin]

Resistance.... yes a little but nothing like it should be.

We took the valve and shims apart and gave them a good cleaning and put them back exactly the way they were....

As far as air goes..... we took a lot of time to bleed and pump the seal in the oil to get rid of the excess air. Pretty sure there was no air in there.

[bork]

Sorry, I'm clueless.

[Adamthomas]

Is that a remote reservoir shock with the reservoir attached by the rubber hose? Never had a 600R, just 650l, and 650R.

[jbehunin]

Sorry, I'm clueless.

Thank you for your insight. I'm looking at all angles here hoping I didn't miss anything...

[jbehunin]

Is that a remote reservoir shock with the reservoir attached by the rubber hose? Never had a 600R, just 650l, and 650R.

No. The reservoir is part of the main shock body....

[jbehunin]

Not my shock, but this is a pic of what mine looks like..

[Adamthomas]

Looks similar to the CR500 shock I just rebuilt. I had to remove the compression adjuster to get all the air out of the shock. It has two small peen marks on the threads. I lightly drilled them and was able to unscrew it. That gave me a good place to bleed the air from the shock. I actually built the shock dry and filled from that hole exclusively. After filling with shock oil, put your thumb over the adjuster hole and tilt the shock to get all the air out that you can, working the bubbles towards the adjuster hole. Top off with oil, and replace the adjuster. Pressurize the bladder with shop air to hold the seal head in place, otherwise you will pull air through the seal and it will move around. After you compress the shock a few times completely, all the remaining air will be up at the top of the shock by the compression adjuster. Let the air out of the bladder, remove the adjuster and top off the shock. Put the adjuster back in, and pressurize the bladder. The shock should have good action now. It's a lot less messy this way and I am certain I have 99.9% of the air out of the shock. Give it a try!

[heart_of_darkness]

If you pull the shock to extension, does it move through its travel smoothly?

I don't know what would cause that behavior, but these shocks are tricky to bleed properly.

I think the nitrogen pressure spec is 212 psi, by the way.

[jbehunin]

Yes the shock will move through the entire stroke.

But usually, if you put about 50 psi in the bladder, the shaft should start to push out, as well as setting the bladder seal and clip. The bladder pushes out and seats fine, but the shaft doesn't move.....

[heart_of_darkness]

My only possible guess is a big bubble of air between the seal head and piston, counteracting the bladder's pressure. An incomplete bleed also causes a lack of hydraulic damping, maybe explaining why there's little resistance to moving the shaft.

What bleeding method did you use? There's basically zero free bleed in the piston/ shaft, so bleeding all the air can be tricky.

[notoriousE-R-I-C]

I did mine in a bucket full of oil. Just to be sure cause it was my first time, Ive only done a rear shock once. I leave it up to the professionals. It was a 95 xr6r revalved it and put a progressive spring on it. And liked it. Heres how I learned;

https://www.thumpertalk.com/topic/763847-xr650l-l-shock-service-revalve/

And I put 200psi in mine

Edited January 19, 2017 by notoriousE-R-I-C

[bork]

You have seen a rebuild or watched a bunch of videos? You tube has many & even racetech.com

https://www.youtube.com/watch?v=hVNNjL7eYCw

http://www.racetech.com/page/id/138

[jbehunin]

Yes I have watched videos in the past but have rebuilt several shocks in the past with no problems. This one is being stubborn.

Put it off to let my head clear for a few days.... I'll try again this weekend.... I'm sure it's something small or dumb.....

[heart_of_darkness]

There are a few critical errors demonstrated in that video. Moreover, these particular XR600 / XR650L shocks additionally require a few extra steps, beyond the usual procedure.

First you need to bleed the compression adjuster mechanism. When filling the upside-down shock body with oil, you need to cycle a flow of oil back and forth between the bladder area of the shock and the main body to dislodge trapped air.

Then, and most important, it's almost impossible to bleed the piston/ valving by the usual method of just stroking the shaft up and down, because there's no free flow (aka free bleed) through the piston/ shaft. Either use a feeler gauge to hold the shims cracked open while bleeding, or drill a tiny bleed hole in the piston, or use a goldvalve which I think comes with a bleed hole.

At the end you need to adjust the correct volume of oil; the above video method collapses the bladder, so its air volume is incorrect. The last step is to fill the bladder to maybe 3 psi, orient the shock body horizontally with the compression adjuster at the highest point, and loosen the adjuster just enough to let the excess oil out without introducing any air.

[jbehunin]

Ok thank you!!! I'll give it a try....

[jbehunin]

Ok here's an update....

Same problem persists.

Do you guys think that I should try the OEM oil weight? I was going to try a heavier weight oil due to my larger size.....

Should I but the OEM seal? I bought an aftermarket seal....

If I was to buy the Race Teck valve kit, does it make the shock better and does it fix this problem I'm having?

Thank you all for your advice!!! I really appreciate it!!!!