I recently fitted an old micron can off my exup 1000 to my fz1 ,after a bit of running i checked the coulor of my spark plug . everything OK bike felt a bit flat in the mid range .I decided to chop exup valve of standerd can and fitted it to my micron. (something i did to my Fzr with great effect)after a good run checked plugs again,spot on . only differance with the valve seems to be slightly more top end . ihope this might help ive been taught to believe that whatever you change or alter be it filters jets or whatever KEEP A GOOD EYE ON YER SPARK PLUGS!