brazing is probably your best bet. If it is leaking though it is probably full of pinholes and welding wont fix all of them. of course you could Kreem it but i think that stuff is trash if you want your bike to last more than a year or two. If you want to check it out here is what i did with my motorcycle when i had a similar problem. It may give you some ideas. http://gstwins.com/gsboard/index.php?topic=41993.20