Taking apart the engine

Hello,
I recently took apart the engine I got with the Cox Airacobra, it was really dirty and seized. I managed to get it moving again but I can not get it started. I want to remove the crankshaft and give that a clean, anyone know how this is done. There is a nut holding to the end of the crankshaft that the prop goes on. I don't know what this nut is called but this is the item that I want to remove. How can I do this without damaging the engine. Also, while I have the engine apart I want to get measurements as I thought I would like to try and build an engine on my dads lathe. I cant find any plans for a Cox engine, nothing with measurements, so I thought that I would get measurements from this one. I think that maybe there could be some gunk in the inlet of the engine. By inlet I mean where the fuel and air go into the chamber. This is something that I will have to look into.
Thanks
Simon

Hey! I watched your UTube. You did a nice job of cleaning the external parts, with the toothbrush and all. Did you flush any cleaner up through the Venturi where the very small hole from the needle valve meets the Venturi?( inside the tube and threaded portion. I'm sure there is a complete, step by step instruction on how to clean and dis assemble your engine. (WD40 Is not a cleaner,  use old fuel or  alcohol = Better results)
Your engine did not look like it has been run that much that you'd need to remove the crankshaft, maybe try dripping some isopropyl alcohol down inside the crankshaft while spinning the crank with your fingers will soften and remove any residue. If it is really really stuck and the heat from a hair dryer won't loosen it up, yah, you'll need to remove the "nut" that holds the crankshaft. CAUTIzoN: although it is hex shaped it is NOT a nut, nor is it threaded on. It is on the splined shaft of the crankshaft and is press fit. There are also some detailed instructions on how to remove and reinstall the prop driver from the shaft.  Simple, easy and safe if you follow instructions.  Let me see if I can find and add the links:

https://www.coxengineforum.com/t6640-cleaning-old-cox-049ers#83537

http://coxengines.ca/dis-assembly-tool-for-cox-.049-engines.html