buddy got a used 2004 450. had blown head gasket. we fixed all the normal stuff thats involved. the top end has recently been done by PO. i inspected and verified this. its got a wiseco std bore/comp piston. reassembled and ready to go. now, i found it to be strange that it had a 52 pilot jet in it.....OBEMR needle (and i forgot the main jet #).... ran way lean with the screw at about 2 turns. hanging idle, instant red hot header, sputtering, etc. (im quite familiar with the YZ's as ive had a number of them in the past 400, 426 and now on an 08 450) all the others including mine and another friends 2003, we;re using a 48 PJ at about 2 turns out. on THIS setup, the one with the 52PJ, it didnt end up running 'normal' until it was a little over 3 turns out. my question is where is this OBEMR needle from and why so darn rich on the pilot circuit? ive tuned a lot of FCR's in the past as well and nothing ever this rich. we still have yet to ride it for a shakedown (ie, track, woods, etc.....so far only the street up the block or so.) but i want to be prepared with jets when we do go out. i was considering putting in a 45 or 48 just to see what was going on.