'80 XJ650 Forks

I recently acquired a 1980 XJ650 which needs very little work. The biggest job it will need is a possible fork seal job (aside from brakes, plugs and an oil change...I don't trust the PO regarding the "recent tuneup"). I don't see any leakage from the seals but they are pretty soft. when the front brake is applied the front end dips pretty drastically. Could it be that they simply need to be re-filled with air or oil? I know nothing about the forks on this bike. Any advice on my problem would be greatly appreciated.

 

If you don't see a leak I would start by draining the forks, each into its own jug. Compare how much is in each jug with the correct amount. If it is just a little low or cruddy worn out I would refill it and see how it rides. If you have different levels in the jugs or not much at all I would take a closer look at replacing the seals. It may also be that your front suspension is shot in which case look into progressive replacements.

 

I have to appologize for my lack of knowlege when it comes to suspension. I am guessing that your refering to the springs inside the forks? Is that what may need to be replaced?

 

Yes the springs inside the forks. They aren't the greatest to begin with so if they wear much they get pretty soft. You should definitely get a book to go with your bike. I am always looking stuff up in my haynes manual. There are some good fork rebuild threads on here as well.

if you dont have manual here are some of the numbers you are going to need to check out your forks

oil capacity (per leg): 262cc (9.42 fl. oz.)
oil type: Sae 10w fork oil
Spring free length: 606mm (23.89in)

 

The front end on these bikes is way too soft to start with. Try a heavier oil and increase the spring pre-load (by around 1") by putting spacers on top of the springs before replacing the top caps (I use a stack of appropriately sized coins).

 

I ordered the Haynes manual for the bike, I just haven't recieved it yet. The bike is running great, it's insured and registered, just needs some minor repairs before I'm willing to take it on any sort of a lengthy ride. I've taken it to work a ouple of times. (2 miles down the road). I appreciate all the top notch advice and input. I will probably tear the front end down tomorrow (if it's cool enough in the garage). I can't wait to get it done and have the bike "comfortable". Thanks

 

You might find what I found on mine, OLD NASTY FORK OIL!!! I think it was the original oil.

 

I would be willing to bet that when I open the forks up the original 31 year old oil is what I drain out of them.

 

My oil was grey and cloudy.

 

After you replaced the "grey and cloudy" fork oil, did it change the "squishy-ness" of the front end? I'm curious if the compressibility of the oil changes after 31 years or if some leaked out over time? I am taking the day off tomorrow from work to tear down the front end and get the job done. That way if I screw something up I have the whole weekend to fix it. I have not ordered new springs yet. I don't particularly mind tearing down the front end again if I need to. I'm goign to replace the seals and oil and see if that helps any. If not, then I'll do new springs. I'll keep everybody posted. Thanks

 

It definitely firmed them up.

 

Well, I couldn't take it anymore so I pulled the front end apart and disassembled the forks. i got the springs out and layed them on the workbench next to eachother. They aren't even the same length. One is at least 2 inchest longer than the other. I'm not sure how this could have happened. I found the springs I need on denniskirk.com and I ordered them and paid to have them overnighted because I am a VERY impatient man. I hope to have the bike up and running by tomorrow afternoon. The weather has been hot here and a nice late afternoon ride would be amazing.