The mixture is adjustable on a k jet, you will need a 5mm long allen key and the adjuster is on the housing between the metering unit and the rubber air pipe to the inlet manifold. There is a hole, fit your allen key down and locate it in the screw, adjustment is out for leaner and in for richer. Remove the key after each adjustment as the weight of it will alter the mixture. You should use a gas analyser to set it up, with practise you can get it close.
Steve.