I was kinda nervous stepping into this project just for the fact you can no longer buy the valves, but after removing the spring for the rear brakes I quickly noticed the piston inside was stuck in place and rust was everywhere. To get my piston out I took a small rod and hit downwards from where the front brakes spring is (into the piston) and it slowly broke loose. I then noticed a lot of the orings were literally desinegrating in my hand. So tonight I'm taking the whole piston up there to get the correct size orings. Now once you start tapping the valve on your hand there is quite a lot of crap that comes out, this really frightened me, but I found a diagram I will post when available that shows the build for an 82-83 proportioning valve. I let the valve soak in gas for 2 days and took paint gun brushed to the inside in order to get any loose rust or debre out. I also let everything that was not plastic and the little spring and thing the spring sits on that came out of the valve stem area. (Anyone know what this spring is? Has a little base for it and is about a centimeter or less tall if you could point it out on the diagram) anyways, I'll be attempting to put it back together in the next couple of nights and will update. Couldn't find any post on it so I thought I should make one