I am converting a Mcculloch 28cc with cd ignition and will be removing the fly wheel.
I will be making my own prop driver etc and want to know how the prop driver is attached to the shaft.
Is the bolt just done up tight and friction alone is sufficient?
Also does anyone know how the flywheel comes off

the flywheel is just held on by friction on the taper on the crankshaft. make the ring for the ignition out of the stock flywheel by cutting the center out using a hole saw or something and clean it up on a lathe and drill it for the magnet, this way the prop adapter is simpler, all you have to do is have it threaded for 5/16" fine thread I think on the crank end or straight through and use a 5/16" fine bolt for the prop bolt.

Mac's are easy to convert

Tap the end of the shaft with a hammer while holding the flywheel, with the engine a half inch above your workbench of course so the engine doesn't have far to fall, and the flywheel usually pops right off. You can't twist them off becaue there is a Woodruff key which you have probably already seen at the back of the flywheel. Nothing to it, this works with most engine, just be careful with any threads on the shaft. Engine shafts are not really that hard, you can smash the end and the threads if not careful. There are other posts that can help with converting Macs. I have worked on a few myself.

Lossen flywheel nut even with the end of crank...support back of flywheel. Tap on nut at end of shaft....bingo the flywheel is loose! Capt,n