Petcocks can be hard to come by, leak often, and are just finicky parts. www.denniskirk.com is an aftermarket snowmobile/motorcycle store. They've got a brass in-line fuel shutoff valve (use w/ 3/16 fuel line) for $9.99 that looks like a cheap and sturdy solution, if coupled w/ an in-line fuel filter. Can anyone think of any real problems w/ using one of these?
(if this link doesn't work, search for petcock under street bikes).