Hi and Welcome to LMF! Before you pull the flywheel, pull the kill wire on the magneto and see if you still get fire. If you get fire, then you've got the kill wire grounding out somewhere. Most mechanics have a flywheel puller but I have taken them off by taking a flat punch and tap around the shaft on the flywheel but not hit the threads. Also put some penetrating oil near the keyway and shaft and when you tap on it the oil will go down around the shaft and help loosen the flywheel. A little upward pressure with a bar will help while you tap on the top of the crankshaft using a board on top of the shaft. Do not hit on the metal end! They have flywheel knockers and work great if you have one. My suggestion will work as I've done it countless times.