@dennis : well what i know from experience is this carb is very sensitive to humidity and temperature, a real race carb where every track and location has its own jet sizes... but if u do manage to tune it correctly.. well.. it's a damn GOOD carb..
EDIT :
besides Keihin FCR, this monster is the favorite underbone road race champions' carb in Indonesia.. by team Yamaha FDR.. and.. u know what.. u can mod this carb so it CAN USE TPS !!... just extend the axle bar on the front.. i think i already post this before..