I'm curious about this question, so I'll ask you a question. Why do you feel it needs to be cleaned inside? Is it no longer performing up to standards? There's an old saying, if it ain't broke, don't fix it. How often do you hear of people tearing down their car (full sized) engines, just to clean 'em up?
Some people are quite good at all things mechanical and even when disassembling something new, seem to do good at putting them back together. Other people would be better off sending their engine to someone who knows what they are doing.
Are you having trouble with your engine? Is that perhaps the reason you want to disassemble it? There's little that can be happening inside an engine that could be repaired by merely disassembling, cleaning, and reassembling, unless perhaps it's all gummed up due to being left with old fuel inside. Even then, much of that can be resolved by just removing the carb and back plate. If something is wrong inside the engine, it's probably only going to be fixed by replacing parts such as bearings, piston/liner, etc.

I almost never disassemble my airplane engines. I guess I'm from the old school. If the bearings feel good and the compression is still strong, I see little reason to open up the engine and mess with it. I do regularly disassemble my boat engines, perhaps every or every other season, but that's because I push them so much harder than airplane engines.

If you're curious about what's inside your engine, removing the back plate is relatively safe. If it's got a gasket, be sure not to tear it. This will let you see the lower part of the liner, the connecting rod, back of the crankshaft, and get a glimpse at the main bearing. Removing the carb is also relatively safe, but all you'll be able to see is part of the crankshaft. I personally do not remove the head unless I suspect there is something wrong with the piston or liner.