I know this forum is mostly bikes but gets a lot more action that ATV Talk and the YFZ is very similar to the YZ. I took the quad out for the first time this weekend since doing all the modifications and it seems pretty good down low - mid range. I'm not sure if its rich or lean up top, but the weather was pretty crappy today as well.
I have a 2006 YFZ450 - stock bottom end.
-2007 MMAD ported head - stock valve train
-MMAD stock bore piston - 14:1 or so compression
-Web +5 cams
-42mm FCR carb
My elevation is right around 700 ft. above sea level.
Right now I am running a 195 main, 45 pilot. NCVQ needle on 4th clip. Carb also has R&D Power Bowl with the adjustable leak jet. Think I'm set around a #40 right now.
Any help/suggestions would be greatly appreciated!