Usually means the engine is not getting fuel. I would check the tank, sometimes the clunk fuel line gets trapped in the forward corner of the tank. So you get plenty of fuel on the ground but when the airplane is titled up like on take off, the engine stalls out because of no fuel. Sometimes a hard shake, nose up and shake the plane tail down with a quick, sharp stop, and the clunk comes loose. Or you may have to take the tank out and do some work on the fuel feed line to shorten it up so it will not get stuck in the corner again. This usually happens after a sudden stop (or even a crash).. Another possibility is a kink in the vent line which goes to the muffler. Or even the connector at the muffler can get stopped up, simple to fix, run a paper clip or stiff wire through the muffler nipple. Think out of the box, what would make the engine quit? If the engine runs good at first and then quits, think of what could cause that. Good luck.