Since you are going to replace the bearings. You can heat up the crankcase and thrust washer with a heat gun or propane torch or oven.
Then tap the crankshaft down, after the crank moves down a little, the thrust washer pops off, continuing will drop the crankshaft out too,
usually the bearings will still be in there, but not always. So I use a brass rod with a lip on one edge (where it has been wacked a lot with a hammer.
I heat up the crankcase again. Then I stick in the rod to catch the bearing race and then tap it out, I repeat for the other bearing as needed too. I work the rod around the edge tapping the bearing out, Usually the Saito engines seem to have the bearings in there real snug so they don't just pop out like the videos show.
Here is a video showing how it is done. Same methods apply to a 4 stroke engine too.
http://www.rcmodelreviews.com/bearings.shtml