You should first remove the backplate, then the cylinder head. Keep the gaskets that come off so you wont have to get new ones when you assemble it again. With the help of a heat gun over the crankcase you should be able to slide up the Cylinder Liner, which is the part that surrounds the piston. After you remove this, you can pull the connecting rod (Thats the part which connects the piston head with the crankshaft) out from the crankshaft and the piston will come out the top of the engine. Then remove the crankshaft from the crankcase and clean everything. You might have to check the bearings for integrity. There are plenty of thorough tutorials on how to do this, including videos.

Replacing model engine bearings [link=http://www.youtube.com/watch?v=TuzEco3EDUM&feature=related]Part #1[/link] and [link=http://www.youtube.com/watch?v=OLSoXPLGzOI&feature=related]Part #2[/link]

These videos are very useful as they will teach you how to disassemble the engine and replace the bearings if needed.

Edit: Now that I read your first post I noticed you are talking about a 46LA which is bushing crankshaft and not a bearing supported crankshaft so there will be no bearings to replace. Still these videos are an excellent guideline.