Check out my site, I have details on how you can modify the petcock so it never causes problems again. From the main page go to the "How To" section and you'll find a link to it there. I'm too cheap to pay for parts when I can modify what I have!
How did the Valkyrie petcock turn out on your bike? I did jamie's mod to mine too. Its starting to leak all the time so I'd like to order the 98' valkerie parts. I noticed its a different number on their site. did you get the COVER SET,COCK 1649093?