One thing that I do, that many others do, is time the engine fuel consumption under the worse possible conditions. Actually, I don't do it specifically to determine how long the fuel will last, but to watch so that I don't get to lean while breaking in a new engine.

So, on a test stand, and a full 12 ounce tank, I set things up, start the engine, then, following break-in procedures, run the engine blubbery rich for three minutes, lean it out for about 20 seconds, then go back to blubbery rich for another three minutes. This goes on until the tank is approaching empty, you can see it when the bubbles form in the fuel line. I time it, for no better reason than because I do, and then I know how long the tank will last, under these conditions.. very rich AND at full throttle... but on the ground.

I then wait about a half hour then repeat the process. Each time, seeing if the time elapsed for each tank is about the same. But, by the time I reach the third tank, the rich, blubbery part, is down to only about 30 seconds and the lean max RPM part (within limits.. not to lean, but lean to get good two-cycle operation and good RPM) for the remainder of the tank.

When I fly, I sort of keep in mind how long the tank lasted during the extreme conditions of max rich and max throttle and go from there. So, I don't run out of fuel, but land it before it ever reaches that point.

Some pilots do this, some do not. Recommended? I don't know. It becomes part of my routine for a new engine, so that's the way I do it. And, it sort of gives me a gauge as to how long to expect a tank of fuel to last and I fly accordingly.

CGr.