I have 96 xcr 600 sp triple with stagared jetting. The PTO cyl. is two sozes smaller than the other two. Cen and Mag are the same. I had just installed the Hotlzman ATACC on it and after a small trail ride I did a plug reading. The center plug was a grey/silver color but the other two were an awsome color. Later at my shop I removed my cylinder head for that cylinder but the piston wasn't burnt, but the top had a grey coating on it. You could scrap it off of the piston but it wasn't burnt. Any ideas why this happened?