Greetings,
As suggested by colleagues I would first check the basics such as valve clearances; the alignment of petrol pies; cleanliness of fuel filters - at the pump in the tank also the tiny one normally situated in the injector. Fully recharge and test the battery.
Have you listened to the petrol pump as you switch the ignition on
You might need to check the petrol line pressure both cold and then hot as there could be a vapour lock when the engine is hot
It is normally possible to clean an injector in a home workshop, by attaching a PP3 9V battery across the terminals to 'open' the pintle; then place the injector up to its terminal block into a sonic cleaner or simply spray carb cleaner through it to try and remove any tarnish which could prevent the pintle operating properly. If this method does not work then take the injector to a PI specialist or Kawasaki dealer for full testing. I used to use a product made by ASNU, see if there is a specialist having that equipment in your area.
Iridium spark plugs will not cure another problem per se but they will operate at lower cranking voltages such as starting. I always fit them to my bikes as they offer superior performance with less chance of fouling.
Hope these ideas help, ask again if you are still having problems and do n't forget to tell us how you finally do cure the problems.
TTFN
Hugh.