It's normal threads. I have found a impact gun works best on them, but if you do not have one there are other options.
If you do not have the pull cord, it makes it very difficult without a impact. Try using a breaker bar and with the engine coming up on full compression, give the bar a quick jerk to break the bolt loose. You can do the same using a hammer, and its more successful. Rather than jerking the handle, hit it with a hammer hard. If still unsuccessful, rotate the engine to pull piston down the cylinder. Remove the spark plug and run some soft nylon rope into the cylinder. Fill it up as much as possible.....but DO NOT drop the end of the rope in the cylinder (it will require removing the cylinder to get it out). Now rotate the engine to remove the bolt. The rope will prevent the engine from turning over without damaging anything. Remember, it must be a soft rope. Do not use a hard one.
If you have the pull cord gear, just pull a bar across the tabs of the gear to hold it steady and remove the bolt. That's an easy one. How I do them without impact.