1999-2002 TRX400EX Fourtrax Service Manual, Page 70Get this manual
FUEL SYSTEM Remove the pilot screw, spring, washer and O-ringCheck each jet for wear or damageCheckthe pilot screw for wear or damageClean the jets with cleaning solvent and blow open with compressed air
CARBURETOR CLEANING
Remove the following:air cut-off valve -thronle valveaccelerator pumpmain iet, needle iet holder, needle jet and slow jetpilot screwCAUTION:
PILOT SCREW
Cleaning the air and fuel passages with piece of wire will damage the carburetor bodyBlow open all air and fuel passages in the carburetor body with compressed air