Small two stroke spits from carb

[steve-V8s]

Have a small, piston port two stroke which won't start. It seems to have good compression, fuel and sparks. However when trying to start it 1 pull in 10 results in a significant pop from the carb. The ignition is provided by a magneto coil triggered by magnets on the flywheel.

I am struggling to figure out, even if the spark timing is way off how there could ever be a route from the plug back to the inlet port. The magnets in the flywheel seem to arrive under the magneto pole pieces at around TDC so if the flywheel has moved on the crank it is not by a lot.

How could it be igniting the charge in the inlet port.

[Bluetec350]

I had similar problem. The flywheel had rotated on the crankshaft putting the timing out.