I've received the CRF 250 petcock and I'm working on installing it.  I realized after I removed all the existing fuel hoses that I'm in a little over my head here.  The fuel hose setup the PO was running was completely different than stock.  Here's what he had - the fuel drain hose (I think) going back into the fuel tank thru the reserve nipple; the on hose going from that nipple into a nipple between the 2 carbs.  I thought the vacuum hose went into the carbs on the left side carb and this goes directly between the 2 carbs.

I'm going to install the CRF petcock but I have no idea what do now that the PO screwed up the routing so bad.  Can anyone help please?!

I had the same problem mounting my CRF petcock when I got it. The lines are hooked up a little differently with it. I hope this link works, it should solve your problem.
http://gstwins.com/gsboard/index.php?topic=43926.msg492538#msg492538