Hi Max, spark on this one is very good, I just can't see why it won't give the slightest kick on the starter fluid, not that this is something new, when I can't get a kick from them I just put them in the non starting pile that I may get back to one day. I am more curious than concerned. If I get a motor that will give a flutter on the starter fluid but will not run on the carby then after replacing the top seal and still no go, then I assume the bottom seal is the problem and that motor goes in another pile.