Hi, just wanted to say this is a great site and you guys really seem to know a ton. I'm working on a friends toro z mower with the kohler sp27 motor. He brought it over and it was knocking at startup and when you shut it off most noticeably. So I did some research and heard these can bend pushrods a bit so I started off with a compression test. When sitting on mower, left side was at 100psi and the right side was at 75psi. So I pulled the valve covers and the rockers and pushrods looked ok...
Koehler command sp27 knock
Koehler command sp27 knock