RM 125X Rear Shock Servicing

[PCMAX]

Does anyone know the quantity of shock oil that is required to service a 1981 RM125X rear shock? The book (Clymer) is unclear as to exactly how much oil is needed.
I have serviced the shock in the past but I think the oil I was using was too heavy & I cannot seem to get the compression damping right, want to try it using 5w this time.
Any tips??

[motomaniac]

Racetech, maxima, motul etc etc.Dont use normal hydraulic oil .It will wear your shock out .
Check that the compression adjuster is lined up and working while you have the shaft out.

[PCMAX]

What part is the compression adjuster? it only has a shaft with a metered/4 way adjustable orifice for rebound damping at the end, a seal at the end, and a floating seal head.
Once again, does anyone have any idea how much fluid (what quantity not quality) I should use??

[motomaniac]

You have to fill the shock and bleed it , it doesn't matter how much it takes . the floating piston should be somewhere around 3/4 of the way up the reservior -  not bottomed out at the end. Rebound adjuster then- but it also affect compression.

[RMJJ]

You want to use 5 weight quality fork oil. anything heavier and the shock will be had as ...............
The quantity is approximately 350ml after you've spilt some.
There isn't a specific amount like quoted for forks.
Basically you just fill it up. The only thing that dictates the quantity is the piston in the resevoir.
The piston should be set exactly 90mm from the schreader valve base of the resevoir.

The way to do it is to fill the shock by pumping it and purging the air and hose, keep the four way ajuster on 1 the lightest, this makes a huge difference to pumping it by hand.
fill the resevoir through the hose hole untill it overflowing, the hose hole is at  an angle as you know so hold the resevoir at an angle to get all the air out.
The holding the hose and resevoir vertical quickly screw them together.

Then charge it with nitro to 142psi

This shock only has the one adjuster which is rebound, compression is fixed

[PCMAX]

Thanks RMJJ, that gives me something to go on.
I don't really get the advantage of 'pumping & purging" though, in the past I have simply dissassembled the shock, disconnected the hose from the nitrogen canister and then filled the shock body until it flows out of the hose. Then I set the piston at 90mm and fill the oil side of the canister, reattach the hose and then put the shaft, fixed piston (at the end) and floating seal back into the shock body. Is this OK or am I doing something wrong 'cause it has always had a little sag and then its hard as a rock.
I will try it this weekend with 5 weight Motul & see how that is.

[LWC82PE]

you gotta pump it to get the air out otherwise you will get cavitation. You cant have any air in the oil at all.

[RMJJ]

You have to purge it for the reasons LWC says.

You can't do it the way you describe. you have to make a container on the end of the hose, then hold this in a vice higher than the shock and draw it through in to the body. I use an 83d resevoir as you can take the valve end out of that.
I suspect the way you are doing it makes it go hard because as you push the rod and piston and end cap in to the body it pushes the floating piston in the resevoir to the top and then there is no room for the nitro so it goes hard. It could also be hard if the shims are blocked up with sludge, have you taken them off the shaft or at least washed them through. Then it could also be hard because you were using too heavy an oil. More than 5w and they are hard as rock,

[CamP]

you have to make a container on the end of the hose, then hold this in a vice higher than the shock and draw it through in to the body. I use an 83d resevoir as you can take the valve end out of that.

Great tip. I was planning on fabricating a funnel with a nut to thread into the hose but I have a spare shock and I'll just use the reservoir from it. Thanks!