No fire

[rotorwrench]

When an engine runs lean, it will back fire through the carb when you add throttle. Perhaps there is a problem with the accelerator pump.

If it has good spark and runs at idle it should continue to run above idle unless there is some form of fuel delivery problem. A blockage or vent problem in fuel supply tank or line, a pin hole in the flex line to the pump allowing air in under suction, or a pump that isn't putting out well could also be possibilities. popping in the exhaust or after fire can be a sign of an internal carb leak or a sticky valve. It also could be a crossed ignition lead.

Things happen that will make you scratch your head wondering why but you still have to keep an open mind when trouble shooting. Always check the easiest thing first and go from there.