I have a Lazer Z with a Kohler Command 25 motor. It leaks a huge amount of oil, but I cannot figure out the source. Placing a piece of cardboard under it has not been helpful in finding the leak.

The oil pools up on top of the motor, between the cylinder heads. If you stand at the back of the mower facing it, the oil is pooling closet to you ( i think it is opposite the carburetor).

Could it be coming from behind the heat shields in front of the cylinder heads? Not knowing much about these motors, it "seems" like it could be valve cover leakage, but it sure is leaking a lot. Any advice or links to kohler diagrams would be helpful.

 

I do not know much bout the particular motor but maybe the top crank seal. these motors should be pressure lubricated so wherever there is a passage and a gasket or a seal it could leak.
valve covers could be an easy fix, maybe first see if they are really loose, cause they do not get tightened very much and seem to work loose over time, any twins I have seen anyhow.

 

I've seen the top crankshaft seal leak on these and it sounds like that may be the case here.