I'm working on a JD 757 zero turn with a Kawasaki FH721D-AS04 25HP engine. Here's the problem: It's burning oil like there's no tomorrow. I did a compression test. Spec, according to one website is 8.1:1 (approximately 120psi). That seems a little low since I got a reading of over 150psi on both cylinders. Wet test brought it up remarkably more. I figured it was good, despite the increase in compression on the wet test. Then a mechanic at the JD store said that the right side head is a high failure item and should be replaced. He said that the overheating of that head causes the valve guides to warp and/or crack under the seals, so you can still have compression and burn oil. I needed to replace that head gasket anyway due to a leak, so I went ahead and replaced the head, valves, valve seals, and gasket. No more leak, but it still burned oil. Next I tried the left head. It didn't look bad, but both valve seals were gone - as in, not there! That was my aha! moment. I rebuilt the head with new seals, new gasket, and relapped the valves. BTW - I did lap the valves on the right side, too. It has slightly more power now, but still burning oil! Could the rings be bad anyway, even with seemingly good compression? HELP! PLEASE! Thanks!
