Ok guys, calm down. 1st off, head work doesn't need to be done by a professional. Try to avoid the use of power tools whenever possible when doing this. All it usually takes to clean a head is a good putty knife and razor blade and some WD-40 to soften the carbon deposits. You want to avoid scratching it if you can.
Next, taking the head bolts off "wrong" will not warp the head. The head was already warped by a blown head gasket and/or previous improper installation. To check if the head is warped, place it on a sheet of 1/4" or thicker glass and try to put a .002 feeler gauge under the head. If this goes under the head and into the combustion chamber area anywhere, the head needs to be brought back to flat. To do this you have 2 options. One is to take the head to a machine shop and have them true it up on a milling machine. The other option (what I do) is to get a sheet of 1/4" or thicker glass and clamp a sheet of 220 grit wet/dry sandpaper to it. Wet the sandpaper and, using a circular motion, sand the head until the entire gasket seating surface has been touched by the sandpaper. (This is quite obviously seen when you do this) Check with the feeler gauge again, then reinstall using the manual for the torquing pattern and values and a <u>new head gasket. NEVER re-use old head gaskets</u>. I have used this method many times and never had a problem.
Now...Jochua, you said you put the engine back in after cleaning the heads. If you disconnected the throttle cable and/or governor linkage and reconnected them differently, it may cause the problem you describe. You really need to get the engine manual, available free from the Kohler website.
Anthony C.-
Your picture of the head is scary. Don't use an angle grinder to do that again, it looks like you removed material from the head and it is no longer flat. You need to fix it with the procedure I mentioned before. A blown head gasket will just get worse.
And, I'll add that I'm 18 but I've been at this for four years, so I speak from experience. If you have any questions, ask, I'll try to answer them or clarify anything you don't understand.