Topic: 77 CB550K Fork Rebuild

[Maraakate]

Hello,

Both forks are really starting to weep so it's time to change the seals.  I have all the parts, read the FSM many times over, and have looked around on here and other places for advice.  I think I can do this job just fine on my own.

However, before I get started I will need something to drive the seal in.  What's the proper size PVC Schedule 40 pipe you guys are using so I can run out and get this before I start tearing things apart?  Failing that, what size of the motion pro fork seal driver tools would be appropriate to use?

Thanks!

[Bankerdanny]

The fork tubes are 35MM OD if I recall correctly, which is about 1 5/16" so 1 1/4OD pipe should work. In my case I have a 30MM socket that I use.

[Maraakate]

I just measured the total size of the seal it's 48mm.

[ekpent]

In a pinch you can use an old seal as a driver of sorts which is what I usually do..

[bryanj]

1 1/4 is smaller than 1 5/16 so would go down the inside of the seal, you need something near to the od of the seal

[Bankerdanny]

1 1/4 is smaller than 1 5/16 so would go down the inside of the seal, you need something near to the od of the seal

You are correct sir. 1.5" is probably a bit too small even based on the seal design.

[Maraakate]

I just went ahead and used the old seal to drive the new one in.  Placed a block of wood on top of the old one after I cleaned it and oiled both seals with some of the fork oil and drove it home.

I put 145cc in there, I forget where this number came from but it was marked on my bottles for this project.  Probably read it on here, somewhere, at some point but I don't remember.

With that said, I looked at the books and there is conflicting information.  FSM says about 160cc in one place, 185cc in another.  Clymer has the same silliness.  OM said about 155cc if I remember correctly.  Is 185-190cc the correct amount to pour in when completely draining the forks and the ~160cc is when doing regular maintenance to swap the fluid?

I also have a fork oil gauge tool.  Have not used it before, but if this helps accuracy I could use that instead.  Mine is 1977 so not sure if things changed between years.  Forks work better than they ever have, and no more leaks so I'm pretty satisfied; but would like to have the proper amount in there.