I'm rebuilding a hydraulic pump for a friend, it is my first one my 4020 is next. The hydraulic pump is a 49cc 3.3. Im going through it cause he thinks its bad, but didn't do any tests before removing. Anyway.. I started to measure the pistons and there a little worn from spec, i measured the inlet valve lift and it is at .090-.1, spec is .82 i think. Just wondering how to replace those valves? and do they come as an assembly? The outlet valves look ok, and the shaft looks ok. I am going to replace the pistons and springs. Is there anything else that should be done while in there? What would the cause be from the inlet valves opening too far? Could i just leave them alone? Thanks for the help in advance.