dutchgs1000g

Aloha.... I have a problem with my gs1000g... on cilinder 3 and 4... I have spark the plug but not in the cilinder.... What have tried: Switching the 1 and 4 lead ... no spark in 4 but a spark in 1 so the lead is working... swapped the coils... no start at al... Replaced the sparkplug with a working plug.... bang in the cilinder... Spray starter fluid directly in the carb... no change in rev... I'm out of ideas.... TIA!