Engine starts and idling when choked, dies trying to rev up

Hello there.
I am trying to get back to life donated to me kz 400. model 1978 I checked ignition and it seems to be OK, compression is fine as well, so here is the problem ...
Engine starts fairly easily and idling quite OK , howewer when I am trying to rev it up it dies immidiately. I beleive it is carb issue - just cannot pinpoit it.
Any help will be appreciated.

Yup, most likely carbs. They need to be spotless and connected to airbox and engine with airtight connections or the bike won't run right.

You probably need to thoroughly clean the carbs.

Yes, remove and clean the carbs
Get a piece of metal guitar string (the type that is coiled) and pass it through all the jets and passages.
Then blast with some carb cleaner.

In addition to what the others said, check out the rubber diaphragms very closely, especially in the crevice where the rubber meets the slide. Pinholes will prevent the slides from raising properly.