Initial timing
Warm it up, then stand by the fender and run up the throttle.
If it starts popping again as you are increasing rpm, start closing down the choke by hand and bring the rpms up again to see if the popping goes away with the now richer fuel air mixture.
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Can try an alternate fuel source of clean new fuel (can with hose) elevated up on a ladder above the level of the carb. Rubber hose directly to the carb.
This will eliminate your fuel pump and possibly the fuel in your tank is still contaminated.
Process of Elimination
Keep eliminating things until you find what the problem is.
Compression
FUEL
Ignition
One thing at a time.