I had the same problem with our 05 i messed with the needle to give it more gas at idle cause these bikes run on the fat side, that worked for a short time, the best thing i did was lose the oil injection and run pre-mix, now it starts every time and idles smooth.
2006 TRX450ER
HOUSER SLICAST L/T +2.5
FOX FLOAT EVOL
FOX PODIUM REAR W/GTT LINK
LSR AXCALIBAR +2
LSR STEM +2
LSR SPROCKET GUARD
LSR SKID PLATE
HRC KIT
K&N DYNO TUNED
K&N FILTER & POWER LID
HRC HEADER/HMF CARBON FIBER RACE CORE
QUADTECH HOOD
JETTRIM STEP SEAT
HIPER REARS 9x9 DBL
HIPER FRONTS 10x5 SBL
ITP QUADCROSS 20/6/10
ITP MXR4 19/10/9
PRO ARMOR FAT PEG NERFS
BLINGSTAR DC RACER BUMPER
FASST BARS
POWERMADD
PRO ARMOR SKID PLATE
QUADFORCE GRAPHICS