adjust your spark gap to .070 standard or 1.2mm and see if it still has spark outside the cylinder. if so, then adjust back to .020 or .030 or whatever you want and you can fully rule out electrical problem and know it's almost certainly carb or compression. heck, slop a little splash of premix down the plug hole then try it and if it won't start after a few good tries you know it's compression or else flooded