Fixing Petcocks
This is an article on how to make the stock vacuum petcocks into standard on/off ones. It was submitted to the Yamaha Triples List and we decided that it should be reprinted here.
I did write the procedure to modify the petcock many times over to the list at times somebody even poked fun at me for what I have done, it is a very simple mod and can be done to most petcocks of the TOGYO brand. All you have to do is to swap the rotating cylinder from left to right I called them armatures, (it is the thinghy that has the pointy lever on it and you apply pressure to, to rotate to RES, ON & PRI positions) on 78 & up models. If you opened these petcocks and looked inside keeping the castle pointing straight up as they are screwed into the tanks, the four holes on the outer body of the petcock resembles the pole ends of an X. The early versions of some petcocks they appear to be at the extremities of a + sign. The X models can be simply modified by swapping the armatures, mandrels, lever or what ever you want to call them. The + models require more work such as breaking the bridge between the two cavities inside the armature. Once you swap the levers and the label plate from left to right the regular ON position will become OFF., RES remains RESERVE and PRI turns out to be ON. The Vacuum is of no use so block the input by threading and inserting a 6/32 set screw with lock tight. Remove the diaphragm spring and replace it with a stiffer one or use a small piece of 5/16 tubing to hold the diaphragm in and you are ready to go. There are a few listers who had done this mod themselves, and have wrote me back that they now enjoy regular ON OFF petcocks.
Well if the description here sounds goofy you are not alone, I tried to read it to myself and felt the same way, one of these days I will just get some help and make a little video or at least capture the act digitally so it would be available to all. May be I will collaborate with Lou and we would have a Kramer and Joe production for you guys. I was lucky to be on the receiving end of some old petcocks that were being returned to the mother ship Yamaha and have a supply that could sustain my collection of 850s with out going out to scavenge for more.
To some listers who were acutely suffering I offered help in resuscitating their petcocks. I do not have much free spare time and that is my problem in not volunteering this help to all the listers. I hope you guys understand it is not that I am not willing but I am just incapable of helping every one.
So if you need more help in explaining the process, or finding help keep badgering me, I like this list and almost every one who has interfaced with me so far. It consists of a fine bunch of people very ethical and varied in knowledge and talents.
Joe. V.