I’m losing track of how many times I’ve had the left hand fork leg off to fix this oil leak. It seems to be from the copper washer under the large damper retaining bolt.
I’ve tried new washers and sealant but to no avail. It doesn’t leak for weeks after it’s reassembled then just when I think It’s good there is a tell tale dribble and a small oil patch under the leg.
Any suggestions on how I can recut these sealing face of the fork leg? Not easy to get in there.
I may try and get it in the lathe if I can hold and true it up with a steady ??

Have you replaced the 509-23158-L0-00 gasket washer on the bolt? Could be a bur on the gasket mating surface in the counterbore of the lower leg. Should be able to chuck it in a big enough lathe, but the outside of the lower legs are notoriously out of round or not true so getting it to run true in a rest is a bit tricky. As for facing the gasket mating surface in the counterbore I'd use a face cutting end mill the same diameter or slightly smaller than the counterbore.

They make piloted counterbore tools... best used with a drill press or mill but can be done by hand drill if careful.

Here's a set on ebay with interchangeable pilots.

www.ebay.com/i/161830878727

And a set for different size screws.... or should be able to buy just the size you need from a good machinist supply.

www.ebay.com/i/161064501615

Get a used fork leg on ebay and swap them out.

Kinda wondering this, when you put your bike in a truck to transport... Do you crank the tie downs hard?
You know, almost bottoming out the shocks?

Yeah I know that just blows seals out. But could it cause this problem too?

Thanks for the suggestions.
It’s not tie down related as the bike has been sat on a hydraulic lift for the last 6 months so the forks are actually extended.
I’ll check those tools out, in my counterbore set the pilot is fractionally too big and I would need to enlarge the hole to suit.
I’ll also order one of the genuine washers as I’ve been new and re-annealed copper items.

Never had one leak if done up tight so i'd be looking for something unusual like a fine crack in the vicinity. Thought mine had a copper washer but i've never replaced them doing seals & never had a problem. Use a holding tool locked into the damper top to stop it turning then swing on the Allen Key with a short tube for added leverage & tighten it Very Tight. Then if it leaks, look further.

I was worried about a crack or something similar, but I have slightly polished the sliders and there is nothing obvious.

I'm waiting to get around to working on this again - too many parallel projects I'm afraid. As soon as as I get stuck on this bike, waiting for deliveries i move onto one of the others. Once the rear light assembly turns up it will jump up the priority list again.

This morning I set about looking at this, as I had fitted the chain guard I had made, not accurate as I had no way to bead roll the edges or press in the trapezoid stiffening, but its turned out ok.

I took the complete leg out carefully to examine. Although the oil was dribbling from the allen bolt area I soon found that the source was elsewhere. The fork seal appeared to be the culprit, which is strange as these were new and the stanchions are new chrome & rust free. When I looked closer I had made the fundamental error of fitting it upside down
So it looked like I had 2 leaks after all that. one of my own making.
I've checked the other side and that is correct so it was just inattention on my part.

All reassembled and left to see it is cured this time.