2006-2012 Honda TRX90 TRX90EX/X Service Manual, Page 83Get this manual
FUEL SYSTEM
SECONDARY AIR SUPPLY SYSTEM (U.S.Atype only)
SYSTEM INSPECTION
Remove the following: Seat (page 2-3)Air cleaner housing cover (page 3-5)
Start the engine and warm it up to normal operating temperatureRemove the air cleaner sub filterCheck that the sub filter is clean and free of carbon depositsReplace the sub fil er if necessaryIf the air cleaner sub filter is carbon fouled, inspect the PAIR check valveInstall the air cleaner sub filter in the reverse order of removalDisconnect the PAIR control valve vacuum hose from the joint of the intake manifold and plug it to keep air from enteringConnect the vacuum pump to the PAIR control valve vacuum hose
Vacuum pump Commercially available
Start the engine and open the throttle slightly to be certain that air is sucked in through the PAIR air cleaner sub filterIf the air is not sucked in, check the PAIR air cleaner sub filte r-to-PAIR control valve hose and PAIR air cleaner sub filter for cloggingWith the engine running, gradually apply vacuum to PAIR control valveCheck that the air intake port stops drawing air, and that the vacuum does not bleedSPECIFIED VACUUM: 60 kPa (450 mm Hg)