You don't state what model you have. I just replaced the rotor on a Champion Model 41302 but removing the stator is the same process.
You will need to remove the muffler and muffler outer protection. Remove the bolts that hold the muffler outer protection. Remove the two bolts that hold muffler to the engine exhaust.
Take a block of wood and place it under the engine to support the generator. The supports on the generator head end will be removed so the generator will tip down and make it difficult to remove the stator.
Remove the generator end cover by removing two bolts.
Remove the two bolts that hold the muffler to the end cover.
Remove the bolt that holds the ground from the generator to the frame.
Remove the two bolts that hold the end cover supports to the rubber supports to the frame.
Disconnect the quick connect electrical connectors and remove the 120/240 volt wiring from the terminal block. See second picture below.
Remove the ground from generator to wiring cable assembly by removing the bolt that connects it to the end cover. Yellow and green wire in picture above.
Remove the bolt from DC brush assembly and pull out of generator. Picture below shows assembly removed.
The stator and cover now can be removed from the generator. Take a rubber mallet to tap on the back of the brackets on the end cover to loosen it. The rotor bearing is seated in the end cover making it hard to remove by pulling by hand. Once lose pull straight out.
The stator can now be removed from the generator end by taking the four bolts out.
The installation process is the reverse.