This Kohler has adjustable valve Lash(their word) and it does have hydraulic lifters. From from the Kohler manual section 11-15: Apply dowward pressure to the push rod side of the rocker arm to compress the lifter and "bottom" the plunger in the lifter bore. Okay there is nothing about making this adjustment when piston is at top of cyclinder? And how in the world can I compress a hydraulic lifter? I had to replace the lifters because one had failed. I put the new ones in a jar of oil(before installing them) and pressed on them to get the air out and oil in ....not sure that was necessary. I tried to press down on them out of the machine and they were rock solid. This is one of my two units that I overhauled during the winter. This one ran one month until this lifter failed....guess I should have replace them on overhaul.