[newtjl]

The backfire is typically caused by gas going into the cylinder without spark, then when you give it ignition spark, it explodes causing the backfire. If the cart is backfiring when you let off the pedal, then press on the pedal, this is the problem. The fix is to adjust the throttle cable and carb so that it closes completely before the ignition spark stops. With me so far? With the key off and seat removed, lightly press the accelerator and make sure the ignition micro switch engages before the throttle begins to open. Adjust accordingly to ensure that happens. If it is randomly backfiring while you are driving it with no changes in throttle, you likely have the piston backwards or the reed valve is shot. The first scenario is the most common though, especially on two strokes.