2004-2009 Honda TRX450R/TRX450ER Service Manual, Page 123Get this manual
FUEL SYSTEM ('04'05)
CARBURETOR DISASSEMBLY
AIR CUT-OFF VALVE
Disconnect the vacuum hose from the air cut-off valveRemove the screw and air cut-off valveRemove the O-rings and slow air jet
VACUUM HOSE Apply vacuum to the vacuum portThe vacuum should maintainedAir should not flow through the valve ports when the vacuum is applied, and should flow when the vacuum is not appliedVACUUM PORT