why does my lawn mower pop when i turn it off?
Answers:
its caused by leftover gas going into the hot muffler and igniting. most of the time its cause you kill the engine before it completely slows down to an idle. could be a weak plug also, but not likely
Other answers:
running rich mix of air/fuel ?
running rich mix of air/fuel ?
Try letting it idle for a few seconds, then turn it off, its most likely unspent gas getting burned.
try releasing the stop bale or lever only part of the way, this will keep the brake from slowing it down to fast. also try changing the sparkplug to a cooler running type.