bertsmobile....I was about to try to correct my original ignition coil statement when I saw your [correct] post.....thanks.
I'm thinking through the charging system connections. The stator [similar to that in an auto alternator] connects to the voltage regulator, the regulator needs to be grounded to operate, and any diode rectifying is likely done by diodes mounted [off the engine] in the wiring harness in the steering column/hood....I know from previously working on 120 amp alternators on marine diesel engines, manufacturers warn you NOT to run them open circuit.....
One alternative for bench testing my lawnmower engine without any mower body is to wire up the regulator, with its own ground, and connect the output to the 12volt battery. I'm unsure if I can just leave the regulator disconnected, leave the stator wiring hanging free and clear, and will post when I think I have figured it out.
Found an excellent stator and regulator test video here:
[Output of the stator alone, unregulated, on this particular Briggs is only about 26 volts....nothing to damage the coils.]
Bottom line: It's safe to run a Briggs engine with the stator wires or the regulator output disconnected or hanging open. Likely the same with Kohler. [This IS different from my experience with my boat diesel alternators]. No need to hang on the regulator and wire it all up for bench testing......
[This video says diodes are in the regulator, not aboard the mower....Maybe Kohler does it with diodes aboard the mower....don't remember where I came across that..]
For those wondering why I bothered posting here, I have been buying, repairing and reselling and modest number of riding mowers each year to keep myself busy...an auxiliary benefit is that my wife won't come down to the garage when I am working...cussing.
So far I have been avoiding rusty mowers that have been sitting but with good engines and wanted be sure I had the right wiring procedures to test run them when disconnected from their mower body wiring harness....trying to diagnosis old mower safety switch malfunctions is [so far] too much of a hassle.