[kevin g]

The rubber diaphragms in my '83 petcock are stiff and have voids in them so it won't work.  I have ordered a new one from Speed and Sports since their price was better than Babbitts even though they have one in stock; it is back ordered until October.

In the meantime, I got some diaphragm material after some searching and plan to attempt making new ones.  The vacuum part is riveted together and I can get aluminum rivets from McMaster-Carr.  The rubber seals that plug the orifices are more challenging.  They seem to be molded on to the piston with a taper.  I am considering trying to use O-rings and I have a lathe to cut a grove if need be.

I was also thinking about trying to find the piston and seal from another petcock rebuild kit.  Has anyone tried that?  I will post my progress when I get time to do this.

[fret not]

One feature that I have found helpful is a "reverse look up" program where you enter a part number and it shows where that part is applied.  A part can be used on many other models than the one it was originally designed for, and it really helps to know where to look when you go looking for parts.

[injuhneer]

The Virago XV750 and XV700/XV920 all have a vacuum controlled petcock.

The XV750 diaphragms can be fitted and the excess trimmed off.

The XV700/920 petcock parts are a direct fit for the Vision petcock.

The other option is a new Virago petcock. They are available on Amazon for about $15 USD. There are many that will fit the XZ tank (most Yamahas of the era used the same bolt pattern for the petcocks).

[fret not]

When I was looking for such parts I looked up the O ring/seal part number, then went to the reverse look up program to see where it was applied.  It covers a LOT of models, and consequently petcocks from those models should fit the XZ.  The petcock I got was less than $10 delivered to my door.  I haven't used it yet so I can't speak for the quality of the seals.

[kevin g]

At least here in the US the petcocks on the 1982 and 1983 are different.  The '83 is unique but you can still get a new one from Yamaha, I paid a lot.  There is no after market petcock for the '83.

[injuhneer]

Here is a rebuild of an '83 valve:

https://advrider.com/f/threads/vacuum-petcock-rebuild-1983-yamaha-vision.1406628/

A quick glance tells me that a simple adapter to fit the '83 mounting would allow the use of another valve.