Eeyore

if its is diaphragms it should tick over okay,

It wont be the exup system that only alters the power characteristics of the engine. You need to go back to basics, if the bike was fine before you filled up it could easily be fuel contaminated with water, this happens when the garage has a fresh delivery sometimes and everything gets stirred up in the fuel storage tanks for a few days. Once you have a misfire for whatever reason, you may foul the more spark plugs so it is worth changing them-dont forget to gap the new ones before fitting, also drain the carb float bowls to remove any contamination and check the filter on the fuel tap if it has one. check fuel is flowing properly from the fuel tap. Then check for corroded or cracked ht leads and caps and all electrical connection on ignition circuit.