How can you adjust engine speed on a kawasaki 6.5 horsepower lawn mower engine?

from the factory the speed is set and cannot be changed, unless you disconnect the coil spring. You can latch the spring somewhere on the housing at your desired speed. this speed is determined by the distance away from the idle stop. example, you can reverse the spring to move stiff lower spring up against the idle stop screw. then using a screwdriver turn the idle screw in to achieve your desired speed.