mystery fork leak

yesterday went to take bike for a ride been sitting on side stand for 12 days. noticed bottom front tire wet thought a small dog maybe marked it went to wipe it looked like oil so looked around right fork noticed cap for ad unit loose an wet inside cap covered in oil, put on center stand forks appear to work normal, wiped everything down, let it sit overnight just looked at it all clean an dry? now im worried is this a sign something going or just a gremlin playing cause I didn't take her out for a week? did check all bolts and screws all tight anyone have this happen? its 83 xvz12tk. p.s. just took closer look and it is wet along inside side of the ad unit is there a gasket or something behind it that could be leaking? and does that involve draing fork to change ? and or brake lines?

yup two o rings behind the ad unit seal it, quick fix but you'll want to put a clean pan underneath cause it will drain the forks

I think you're referring to the anti-dive valves....On my 83, my anti dive valves started leaking fork oil at the valve shaft slider. The shaft slider is the internal rod that the brake line pressure moves to restrict the oil flow for anti-dive. When the first one started leaking, I was able to buy a new one thru Yamaha, but that was a long time ago. When the other side started leaking, I was able to buy a used one from somebody on the Venture site I used back then. When I installed the Progressive fork springs, some Venture owners suggested that I eliminate the anti dive, so when I installed upgraded brake lines, I disconnected the brake lines to the anti dive valves (to improve brake lever feel). Then I had a machinist buddy of mine make up plates that allowed flow between the fork ports to eliminate the possibility of them ever leaking fork oil again. You can't just block off the flow between the fork ports because that would put them in the anti-dive mode. First, replace the O rings in the fork ports, but if that doesn't eliminate your leak, the valve itself is your problem. If you have a leaky valve and want to keep the anti dive operating, you probably could take the valve apart and replace all of the O rings. You can get a metric O ring kit at Harbor Freight. I've never taken an anti-dive valve apart, so I don't know for certain if it has anything other than o-rings in it though.