81 XJ650H Fork Seal Replacement

I was just looking at my low mile beauty and I see oil on my fork tubes. I just can't beleive it. My fork seals gave up at the super low miles just over 6K. I guess they died of old age.
I don't have a book on this one. Does anybody have a write up on changing these out. It looks alot simpler that the 750 forks. It looks like there is an allen bolt that holds them at the bottom. Is there anything I should know before I take these out?

Thanks
MN

 

I did them on my 550. The only hard part was when the part inside the lower tube that the allen bolt threads into started to spin. The other end (accessible only from the top of the upper fork tube) is like a socket. You need to insert a hex end into it to hold it (I think it was 19mm). I had to rig a socket extension and a socket with a stack of nuts in it, the last one protruding from the end, and stick that in to hold it while turning the allen. The Clymer manual didn't address this at all.

Buy new C-Clips, too.

Also, I bought seals from Pyramid Parts in the UK and wasn't too thrilled with them. They still leak a bit. I think I'd go with Yamaha seals next time.

 

Had to replace the seals on my old 1980 xj650 that I,m rebuilding. I made up a tool by welding a 19mm head bolt inside an appropiately sized tube,works perfectly. You can even weld a T piece on the top, just like the pro. unit, cheers. 85 xj900 daily ride .xj650 rebuild after sitting in my shed for 23 years

 

Also, I have a repro of the factory damper holding tool available, if you don't want to have to cobble one together from bits and pieces.........

 

I used 12mm studding 2x19mm A/F nuts tighten up against each other at both ends - dropped the studding down the folk until it registered - held a spanner at the other end and used an allen key with tommy bar to release the component.

Worked just fine.

 

These things are as simple as it gets. Check out Gamuru's how-to in the FAQ section. I followed it when I changed my fork seals and had no problems. He's even using a '81 XJ650 in the how-to. The only thing I struggled with a bit was removing that allen bolt. That is, until I finally grabbed a spark plug socket and made this tool:



The back side of the spark plug socket is just the right size to hold the damper while you loosed the allen bolt. Just add a couple more extensions to reach down in the fork leg.

 

That is a rather low mileage to have the seals die, although TIME is factor as well and they are probably just dried out. Then again, I had one fail on my Norton when it was only about a week old.

When you have the forks apart, take a CLOSE (even use a magnifying glass if you have one) LOOK at the fork tubes in the area swept by the seals. Make sure the leaky fork didn't take a well-placed stone and now has a ding in it that will drag fluid past the seal, or has ragged edges that will wreck your new seal too. Minor imperfections can be cleaned up with judicious use of a fine stone and metal polish.

Just another argument for FORK BOOTS!

 

just did mine the dampener nut is a paing if you havnt got a tool for it. plan to make your tool ahead of time. i made mine from all thread washers and nuts ... i used a bench grinder to cut teeth into the washer.


not having this cost me 2 hrs ( had to figure it out) 3hrs 30min for my first one, 15 min for the second one.

 

+1 on the dry seals. 28 year old fork seals, even low mileage ones, can't be trusted.

One note about fork boots: depending on your normal riding conditions, fork boots can do more harm than good. If you ride a lot in rain/wet/damp conditions, fork boots can trap moisture around the seal area, causing premature wear and the possibility of getting water inside your forks. Water is a killer for fork internals.

 

Don, great picture of the cylinder holding tool. but my question is how do you prevent the spark plug socket from spinning as well?

I see you have extensions but to me it looks like the extension is just sitting in the socket. obviously you need something either six sided or 12 sided to fit inside the socket and stop it from spinning. what can you use?

side note: 3 forum threads in xjchat about fork seals! great minds think alike

 

the outside hex of the socket sits in the hex shaped hole on the bolt. The socket can't turn because you put a rachet/breaker bar on the top side of it which is not pictured.

 

if that is a socket then what is the long part? a six sided extension? i understand a rachet goes on the left part of the extension but how are those two components shown in the picture connected so there is no free plaY?

 

It's a regular extension.

it's a spark plug socket turned upside down with the extension through the big
end where the spark plug would normally go and into it's normal 3/8 square.

Not all spark plug sockets are cut all the way through to allow the extension to fit both ways so check before you get started.