MikesXS Carbs VS Vacuum Petcock

[TysonS]

Hello all I recently began my journey into a a 78'/82' Yamastein! I have ran into a situation where I need some clarity. This is my first motorcycle project that I have basically had to start from scratch so my knowledge on these things is maybe not up to par. From what I can tell from the Youtube and the Forum is that my 82' Tank has a vacuum petcock this I am sure of. My issue is that I purchased the bolt on pre assembled carburetors from mikesxs and there does not appear to be a vacuum connection. Video's I have seem say that there is a spot to drill out and tap for a hose barb, the issue is I am only keeping this tank for the safety requirements in this province then I plan to chop it and install a new tank with gravity feed. Does anybody have a petcock work around to gravity feed? Or second option would be to drill either the carb or the aluminum boot that was supplied with the carb? I would prefer the petcock modification as I am worried that it may not work anyway given the age and condition it was in when I got it. Any advice would be greatly appreciated.

Thanks

 

[CaptChrome]

Welcome to the forum.

There are some gravity drain petcocks made in Taiwan available for not a lot of money. But, there are two types that I am aware of that differ by the center-to-center spacing of the mounting bolts that go into the tank (the later model tanks use a larger spacing). Make sure to measure the mounting bolt holes on your tank and then search for the petcock based on your measurement.

My 1981 tank uses a 46mm center-to-center mounting flange (this flange is shared with the 77-84 XS650 petcocks). Performing a search for my bike ("yamaha xs 46mm petcock") returns a bunch of sources. You should be able to do the same using your measurement and find a source that is reasonable for shipment within or to Canada.