How do you seperate the engine from generator.

Assuming that you intend to someday put it back together, do this:

1 - Make it safe by taking the wire off the spark plug and getting all of the gas out of the tank.

2 - Remove the stator part of the generator. There are 4 long bolts with 7/16 inch heads that hold it onto the adapter plate at the engine end of things and a 1/2 incher holding the end away from the engine down on the frame. Some generators have more than 1 frame mount, these are harder to get out, I use a channel lock pliers to hold the rubber mount and a socket to remove the nylock nut. When it's all loose, pull the molex plug out of the distribution panel (where the outlets are) and then gently slip the stator off of the rotor. Try not to break the windings.

3 - Support the engine/rotor assembly by placing a block of wood, stone, or metal under the rear of the engine.

4 - Take the long bolt out of the end of the rotor. Use a 6 point socket for this so as not to mess up the bolt head. This is also much easier with an air ratchet. The rotor shaft has an "innie" cone shape milled into it and the engine has a corresponding "outie" bevel that fits inside the rotor shaft. This is called a tapered shaft mounting. You can get the rotor off of the engine shaft one of 2 ways...
The "official" method:
Get the kit from Briggs and Stratton, tap threads into the inner surface of the bolt hole, insert the appropriate threaded rod and torque it to pull the rotor free. This only takes one tech.

The "redneck" metohd:
You need a friend you trust to swing a hammer, a fairly heavy hammer (I use an 8 lb sledge), and a chunk of 4 X 4 wood long enough to act as a punch when placed against the rotor laminations. Turn the rotor so that the laminations are horizontal. Put the 4 X 4 against them as far away from the engine as you can without breaking the plastic parts of the rotor. While holding the 4 X 4 tightly against the rotor, have the other guy whack the other end of the 4 X 4 sharply and with a good amount of force. Then rotate the rotor 180 degrees and whack the heck out of the other side. Repeat this process until the rotor pops off of the enigne shaft.
My old shop mate and I got good enough at this to take the rotor off in 2 whacks every time.

Regards,
Carl