Every experianced guy will tell you that the factory setting are just a starting point. That is what they are. You will get the engine to crank but you will have to tune the enigine for your specific situation. At first I just wanted my gassers to crank up and fly. Heck my weed wackers ran perfectly out of the box for years with no adjustment. I tried to carry that rational over to my plane engine. You just have to tinker with it till you find the sweet spot. Your best bet is to find someone who had experiance with gas engines and ask for help. That is what got me over the hump.
I have been flying a Giant Aeromaster with a G-62 on it for about a month and I still don't have it running like I want. Sometimes they tune real easy and sometimes they take a bit of patience.