RE: phoenix models yak 54
I wouldn't use a razor blade the dremmel with the sanding drum wurks well that is what I used to make the hole for my Saito .72. I started with about a 3/4" hole and opened it up from there. didn't take long just a few minutes. I just run an extra line from the 3rd vent line in the stopper in the tank and run the hose out the bottom of the plane and put a small screw in it, I remove the screw to fill it up and put it back in when I am done.