Last year i found an oil leak was coming from my speedo drive, so i took it out to inspect, there was an o ring fitted that seemed worn, after trying to get a replacement with no luck, i replaced it with a metric one i had from my collection, it seemed to cure the problem, until now, ive searched again for the o ring with no luck, even dragonfly and burton bikes bits do not show one on the engine blow ups, So if that's right and it was something the previous owner fitted, what actually stops the oil from coming out, the drawings show 2 washers.10365-3375 & 10265-3395 do either of these stop the oil getting past the drive, the funny thing is there is a cut out on the shaft that makes it look like it was made for an o ring.
My bike is a A65 star.
