This is more complicated than I should try to explain in my own words so I am sending a Repair manual.
Since you didn't;t tell me the model number or even if it was a vertical shaft or horizontal shaft engine, I had to guess which one you had.
Here is a repair manual for the 25 hp command VERTICLE shaft engine.
If this is not right, let me know and i will get you the other one.
Here is the closest manual I can find.
It should cover all of the engine like yours from 18 hp and up.
If this isn't right, then you may need to find the manual at this site. Using your EXact Model numbers. http://www.kohlerengines.com/manuals/landing.htm