Thanks for posting that Mark. Successful draw filing requires managing to keep the file level, which is the hard part, plus achieving a fine finish. The best way I've found to achieve that finish is to use a full-sized second-cut file, and keep the teeth clean. The old guys used to rub chalk across the file frequently, which works for me with a bastard file if you are pressing too hard and causing chips to stick in it, but for draw filing aluminium I use a different system. I just keep the file card handy, and card the file every 15 seconds. You must still use very light pressure of course, and remove the swarf every 15 seconds when you clean the file.
Of course you also change from filing along the tank to across it each 15 seconds, since draw filing can only generate flatness in one direction at a time.
Remember to check the underside of your carburetor, now that you have the tank-top flat. Either or both parts can be bowed.
Your tank top looks as if it was bowed quite a long way, incidentally. Your PulsaPrime carburetor is not really sensitive to going rich due to a bowed tank the way the original PulsaJet was, but it would be a lot to ask, expecting it to work properly with a tank as curved as that. The limit for the original PulsaJet was 0.002" hollow in the center, measured with a straight-edge right across the whole tank. The same applied for the flatness of the bottom of the carburetor. I had a 92908 that went super-rich, with a bow of exactly 0.002" as closely as I could measure it, and it worked perfectly again after draw filing it flat.
