Probably would be best to just go ahead and buy a new spark plug, anyway, as they don't cost that much. Is it getting fuel to the cylinder? If it is, then, it sounds like you might have a stator, pick up coil, ignition coil, or CDI issue. After cranking it over for a minute, take the spark plug out and look at the end of it and see if it is wet with fuel on the end of the plug. If it's wet, you are getting fuel. If you think it is firing, but not getting any fuel, pour about a teaspoon of fuel into the spark plug hole. Screw the plug back in, quickly before it evaporates and put the plug wire back on and try to start it. If it is firing, it should start for a second or two, until it burns the fuel out that you put in. That is, if it is in time and has compression and is firing, it should start. If it don't start, you need to check the firing. The easiest way to check it, if you don't have one of those firing testers, is to pull the plug wire off the end of the plug. Take a phillips screwdriver and stick it in the end of the spark plug wire boot, making sure it tips the metal piece inside. Lay the metal piece of the screwdriver close to the head somewhere. About 1/8 to 1/4 inch away from the head should do. Make sure the kill switch is in the run position. Crank the engine over. Fire should jump from the metal part of the screwdriver to the head if it's firing. Remember, if you are tipping the metal part of the screwdriver or the wire, you will probably get shocked if it is firing. Actually, it would be easier to test the firing first. Then if it don't fire you can pour gas into the spark plug hole and try it. The spark should be bright blue. If it is orange looking or you don't have a spark at all, then, you have a firing problem. If this is the case, then, you will need to check the resistance across the stator, pick up coil, and ignition coil with an ohmmeter. I don't know what they should read off hand. You will probably need to get a repair manual. If it's not one of these, it might be the CDI. I don't know of anyway of checking the CDI, except to replace it with a known working CDI.