Small Engines (Lawn Mowers, etc.): 18.5 HP Briggs Engine No spark, hp briggs, weed eater

Question
I've got an 18.5 hp BS 2 cyl engine on a weed-eater riding mower, not sure of the age.  It has no spark.  I pulled both plugs and tested both wires.  The mower was running fine, i shut it off, then it wouldn't start 5 minutes later.  Now, 3 days later it still won't start.  There are 2 wires coming from under the flywheel, a test with the ohm meter shows they are both grounded.  Is this normal?  

Also, i disconnected all wires from everything (attemting to bypass any kill switches) except the plug-wires (magneto) and starter button.  I figured this would let me know if the magneto was bad, is this valid, or does the spark to start the mower rely on somthing other than the magneto (batery)? I couldn't find any other path to the plugs other than the magneto, so i assumed this would be ok?  

Answer
Hi Joe,

You have done most of the work.  I'm not sure what coil wires go where without seeing it.  You will need to trace them away from the coil to see.  The coil is most likely bad.   Just make sure that the gap has not moved from it's .012 gap and that it grounded.

Let me know how you make out.
Michael