Ignition spark

Hi all on my kz 750 e1 it keeps dropping a cylinder then I change the plug and then runs ok for a bit then drops cylinder again any ideas thanks Andy

What does the plug look like when you take it out? Is it covered with dry, black soot? Wet, black oil? Is it as clean and shiny as when you installed it?

It looks like slight sooting when I take it out
And I replace it with new plug

You may have a carburetor problem on that cylinder, or possibly a problem in the secondary wire from the coil.
Is all of the routine maintenance up to date? Especially valve lash?
Has the fuel level in each carb been verified using the clear tube method?
Do the secondary wires ( the ones from the coils to the plugs) look relatively new and are they supple? Are they stiff,brittle and cracked? How do the boots look?

All ignition side is good boots new leads new have clear tube the carbs I will do a valve lash and see what happens and a comp check