I've got some NGK iridium spark plugs CR9EIX for my 749 few days ago. Today I tried to install them by starting with the front cylinder, I was able to get the original Champion plug out but when I try to put the new plug in, the last 1cm of the hole is too narrow that I can't screw in the new plug completely, the tool is hitting the last bit of the hole. Was lucky that able to get the new plug out. I checked the construction of the two plugs turns out the champion is a bit longer than the NGK. Suppose to be alright if I could find a spark plug tool that is thin enough to fit into the last bit of the hole. Not even the tool that supplied with the tools bag could fit. Anyone has done this NGK installation or any idea?