2004-2009 Honda TRX450R/TRX450ER Service Manual, Page 114Get this manual
LUBRICATION SYSTEM (After '05)
PISTON JET
REMOVALINSPECTION
Separate the left and right crankcase halves (page 16-11)Remove the bolt and piston jet from the left crankcaseCheck the left crankcase oil passage for cloggingClean the oil passage
Remove the piston jet shaft from the piston jetCheck the piston jet for damage or cloggingBlow open the oil passage in the piston jet and shaft with compressed airPISTON JET SHAFT PISTON JET