have you tried using jump leads connected to a running car - it might sound odd but cars have a higher cranking amps and turn the engine over faster - yes it sounds odd but i have had bikes that failed to fire and then once battery died i hooked them up to a car and they firedyou will know what i mean if you have tried this - but be a little wiser with the starter as a higher amp means more power in the starter and therefore more heat blah blah blah etc etc etcthis will show you if most things are working correctly and start to point you in the right directionsecondly when you said had carbs cleaned do you mean CLEANED CLEANED or just old fuel taken out - were all your jets cleaned out - did you give all the orifices a spray with carb cleaner left to sit and later sprayed again-personaly im thinking your jets are blocked but it all depends on how cleaned they were (the pops and bangs are the easy start and fuel your putting in the cylinders im guessing you are using something like easy start as you said sprayed into the carbs)
it was running fine 45 minutes before he changed the oil, filters and plugs then nothing!