Petcock diaphragm styles

[Sheldon Brown]

New to XS650 and this forum. Can anyone help me identify the diaphragm with the large black pad.
This is from my 78 XS650 Special, the kit (200-2014) has a different style with the o'ring which seems to be all I can find.
Working with Mikes but they haven't found one yet.
The rest of the kit is correct, I really want to save my originals.
Thanks in advance
Cheers
Sheldon

 

[Jim]

I don't think that's an XS650 diaphragm. I've rebuilt several from various years and they all looked like the Mikes replacement in your pic. Show us the whole petcock?

Oh, and welcome aboard!!

 

[Sheldon Brown]

Here a are a few more pics.
I really suspect these are original as the bike only has 11, 000 km (7,000 miles) and has been in storage since 1991.
This bike is for my wife and I would like to keep the vacuum shut off feature. I picked up a kit 200-2014 from Mikes and everything else appears to be correct. On my diaphragm the plastic piece is part of it, assembled then end rivetted
Thanks for the welcome message, I have used this site a lot already, just now joined
Cheers
Sheldon

 

[jetmechmarty]

I’m pretty sure that’s not an XS650 petcock. It could easily belong to another Yamaha, but I wouldn’t know which one. There’s no reason not to use it if you can find the parts.

 

[Sheldon Brown]

Somewhere in last few days I saw post on how to convert to manual operation, it including plugging one port and switching the levers side to side. Cant seem to find it again. If I can find that post again I would consider it.

 

[jetmechmarty]

Somewhere in last few days I saw post on how to convert to manual operation, it including plugging one port and switching the levers side to side. Cant seem to find it again. If I can find that post again I would consider it.

You simply deactivate the PRIME circuit. I think vacuum petcocks are great when they’re functioning properly.