Hi Trev, yes I did look at the cork washer in the timed breather and it was OK but I had to use the thickest cork supplied and I noted that the locating dowel was only just connecting with hole and I'm wondering if it has slipped out? I guess I will just have to take it apart to see, but I think the main problem is the bore, it was a bit worn when I did the motor and I think that blow by is the maim problem although it doesn't blow any smoke out the exhaust, it has done a bit over 13000 Ks since the re build and it is running quite nicely considering that it was built out of bits a peace's even the crankcase is not a matched pair, so I think I will put up with the oil leak and just ride it while I still can, only another 6 years and they will take my motor bike licence of me, 85 over here.
Peter