Where is a good place to buy a new fuel petcock for my 73 rt3 360 thanks

I prefer to rebuild the original. Kits are available on Ebay. Used originals on Ebay too. Others will be along to advise on new ones.

You can still order new from Yamaha, although the original part # has a new part number
214-24500, it looks different but will mount and work the same, make sure to buy a new rubber oring (it may come with it, I don’t remember) and the washers for the mounting screws, you may have to cut the brass tube to match the length on your old petcock for the reserve function to work properly. This is an option if originality is not an issue, as said earlier the individual parts or kits are available to rebuild your old one, as simple as they are for some reason I have about a 75% success rate on rebuilding them, for a cost comparison the rebuild parts may be more $$ than just buying the Yamaha brand new part, also there are a lot of aftermarket (non genuine Yamaha) available for even cheaper, I personally prefer the genuine Yamaha as the quality is much better. This new one and other genuine Yamaha petcocks that are available with the difference being either fuel outlet is straight down, left outlet or right outlet, there is a very good thread somewhere on this forum showing the ones that will work with their corresponding part number.

Hi thanks for the info yes it's leaking where it mounts to the tank I would buy just the o-ring and washers for the screws if I could find them the screen for the reserve does have a tear in it not sure if that really matters other than that it works okay

The oval oring is part# is 214-24512-00-00
the mounting screw gaskets 90202-05187-00 
I just checked my parts stash and the new 214-24500 petcock does come with a new oval gasket, which is good because Yamaha wants like $18.00 just for that oval oring, this is why I mentioned buying individual rebuild parts will cost more than the new non original looking but performs the same part, the mounting screw washers are NOT included in genuine Yamaha petcocks and are also ridiculously priced at around $3.50 each. 

Thank you I'll check online to see if I can find them

Thanks guys I just ordered the o-ring and gaskets from partzilla only $20 for the parts but another $10 for the shipping I had already rebuilt the shut off part of the petcock so that is good this way I keep it all original kind of pricey though

Buy big when you do Partzilla. Shipping can and will be a bummer until you hit the " Free Shipping " mark.
But that doesn't always happen with our orders, same for the other companies .

RMATV has a much lower minimum order for free shipping and WAY better service in my experience.. 

 

And RM ATV MC's Yamaha OEM manual goes back model year-wise farther than some other online stores! Motosport, for example does not go back as far.