Re: Petcock/Gas tank
It appears to be plastic (drilling & tapping won't work) and has a barbed fitting/nipple on the bottom. If so just install an in-line petcock and locate it between the engine and tank. Most any petcock will be threaded, either male or female or one of each. You can buy barbed fittings that will thread into the valve (petcock). You didn't say what engine/carb you have but 1/4" or 3/16" I.D fuel tubing and matching barbed fittings will suffice for most bike engines.
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