KZ is a north american model i think? could be blocked pilot jets,had similar problem on an XS, must assume the bikes been stood awhile and the carbs are/were gummed up? Also being a kz will most likely have diffferent size jets to the uk model Z650, try a colourtune kit to check out if the ignition is ok at low revs, also check float heights and check if float needles are sealing correctly, have the carbs been vapour blasted? hope thats some help.
Perry, September 2014
