Does the dealer sell a kit to rebuild the frame mounted shutoff valve. Took mine apart and a small part on the vacuum end was trashed. And the o-ring was very bad too. Is this something they'll have or a special order?, or are they going to sell the the hole damn thing? Price?

I know of no rebuild kit. It sounds like you are in the RES-PRI-ON switch. You might be able to source the o-rings in any of the delivery system, but you would need a good metric parts supplier.

Basically your choices are new, eBay (take a chance), or GSTwin commerce department.

As the 89-91 era bikes approach 20 years, we need to get used to this type of thing.

You could always get rid of it by making the line go straight from the tank to the T in the carbs.

How do I do that. What about the vacuum lines. Need directions please? Thanks.

http://www.gstwin.com/racers_corner.htm#pingel
I this is your wife bike I might not do this but here is the link.
You also can get a new one fron parts411.com or bikebandit.com