I pulled the spark plug on the wife’s EFI'ed Burgman 400 scooter at 600 miles and the ground electrode area is a nice enough tan color but the perimeter threaded area is blacker than I would normally have expected and the center electrode is a tad blacker than I would normally have expected.
The plug also has a discoloration on the first few turns of the thread and the plug was definitely not tight enough in the cylinder head.
The perimeter blackness of the plug suggests to me that it might be burning a tad rich or the plug overall might be running a tad cool.
Also given that the plug was not tight enough there may have been some small amount of blow-by past the plug’s fist few threads.
I am reluctant to switch to the next hotter range although I have that option according to the manual. As it stands there is no knocking and it runs fine. If it wasn’t such a bitch to change plugs I would run the next higher heat range for a bit and see.
Lots of Tupperware and an engine that is more buried and inaccessible than either my former Honda GL1500 or my new-ish '04 Honda VFR ABS! For a few bux more you’d think Suzuki would have built-in a few removable access panels to facilitate transmission oil access and valve adjustments etc. I am replacing the NGK CR7E with a new one.