I have similar problem, my new engine will not run. I have good visible fire at the spark plug gap, but in looking at the spark plug after trying to crank it at full choke for many times the plug always looks dry. In removing the carb and intake throat piece, i can see the piston moving up and down easily, however the top of the piston doesn't appear to drop below the top of the opening so I don't know how the damn thing can be getting fuel into the cylinder chamber. I removing the the head there are two tin gaskets there and again the piston is clean and moving up and down easily, anyway based on this info does anyone have any ideas on how to get this thing running. Thanks