When your talking a 6 or 7 needle are you talking the slide? needles have numbers like longer numbers like 83cm98, slides have numbers like 5, 6, 7,or 8. the K5 has a 7 slide stock, I go to a 8, it cleans up the bottom end. I don't like Kawasaki's jetting, it seems always rich, really rich, I'm at 3400' elevation. Get a Lectron carb idles smooth and is very responsive.