Topic: SLOW rebound after fork refresh

[DurangoCB]

I put new seals and fresh 15wt oil in my CB500 K0 forks today.  The first leg went back together and functions normally, but the second leg rebounds really slowly (takes 2-3 seconds for it fully extend after compression) and feels quite "crunchy" during compression, like the sound of the spring rubbing on the sides of the fork tubes. 

I can't imagine as low-tech as these damper units are that it's faulty, but I pulled the leg apart again and blew the damper out with a compressor.  A blob of sludge did come out and land on my favorite sneakers, but that's it.  All the ports are clear.  I also double-checked that the new seal wasn't in upside-down then reassembled... same thing still.   

Ideas?

[DurangoCB]

I have the damper unit removed again.  It's stock at both the top and bottom of its travel, as if there is build-up on the inside walls of the cartridge on both ends. 

Are these units serviceable? 

What are the internals made of?  Can I submerse the entire unit in a solvent of some kind or are there rubber pieces inside? 

[robvangulik]

The fork seal and the o-ring on the top screw are the only rubber parts.
There must be more sludge in there!

[Bodi]

It's just a steel cylinder, no rubber parts. The "piston" is a fairly tight fit in the cylinder, but I can't think of what would be stuck in the bore. Can you see anything when looking down the hole?
I think 15wt would be a bit thick btw.

[Deltarider]

Could it be that you, during the job, had the leg in a vise that was tightened too firmly?

[ekpent]

 Does the spring slide in and out easily from the top. A bent fork tube can cause some drag on it as I found out on a project once.

[DurangoCB]

Thanks fellas.  It is definitely the damper unit.  When I remove it clearly the piston/plunger is sticky, particularly at the top and bottom of the stroke.  I have both fork legs apart so I can soak the dampers in diesel for a couple days. 

I'll be sure to follow up at some point to button up this thread, since I have had such a booger of a time finding anyone who has posted about this problem online.