When it came time to remove the stanchion from the fork leg, I was able to loosen the allen bolt, but as most people experience, the bolt then just started spinning the damper rod in the bottom of the leg, not allowing you to get it undone all the way to pull apart.
After a lot of playing around with putting the fork back together to see if it would hold the damper rod, I jumped on the net and did a fair bit of reading and found that you need to either slide in a piece of dowel and apply downwards pressure or build a tool to hold the damper still.
After reading just about every forum I could find about xs650's I stumbled across one post that stated that it was 1978 that the damper rod was changed over and bikes that where made in mid 78 or later like my 81, need to have a 17mm hex bit inserted into the top of the damper rod to hold it still. Not having a 17mm hex bit, I read on and found that people have sometimes used threaded rods and several 10mm nuts to insert down the fork tube to hold the damper, as a 10mm bolt/nut has almost a perfect 17mm diameter on it.
I checked my toolbox and through the garage but just happened to have everything but a 10mm bolt and nuts, so I ran down to Bunnings and grabbed a bolt and 2 nuts to make my 17mm hex bit.
With a bit of thread lockerI spun on the two nuts to the bolt and tightened them up as much as I could and let the thread locker cure over night, and this evening put together the tool that would hopefully let me get the fork leg separated.
I grabbed my largest extension bar, a reducer and my 17mm socket and put in my handmade 17mm hex bit and slid it down the fork tube, and grabbed my allen key and went at the bolt and sure enough, with a few turns it loosened right up and the stanchion and the fork leg separated.
Over the next few days I will now clean out the inside and outside of the fork parts and then replace the oil seal, and then do the same to the other fork.
Here is the tool and the extension bar I used get the damer rod allen bolt out.
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