Honda CB900F Service Manual page 65

MAINTENANCE
SECONDARY AIR SUPPLY SYSTEM
PAIR REED VALVE
CYLINDER HEAD
COVER
~I
This model is equipped with a built-in secondary air
supply system. The pulse secondary air supply sys -
tem is located on the cylinder head cover.
The secondary air supply system introduces filtered
air into exhaust gases in the exhaust port. The sec-
ondary air is drawn into the exhaust port whenever
there is negative pressure pulse in the exhaust sys-
tem. This charged secondary air promotes burning
of the unburned exhaust gases and changes a con -
siderable amount of hydrocarbons and carbon
monoxide into relatively harmless carbon dioxide
and water.
Check the PAIR (pulse secondary air injection) tubes
between the PAIR control solenoid valve and cylinder
head cover for deterioration, damage or loose con -
nections. Make sure that the hoses are not cracked.
If
the hoses show
any signs of heat
damage, inspect
the PA IR check
valve in the PAIR
reed valve cover
for damage.
EXHAUST PORT
Check the air suction hose between the air cleaner
housing and PAIR control solenoid valve for deterio -
rat io n, damage or loose connections.
Make sure that the hoses are not kinked, pinched or
cracked .
PAIR CONTROL VALVE
AIR SUCTION HOSE
EVAPORATIVE EMISSION CONTROL
SYSTEM (California type only)
Check the evaporative emission (EVAP) canister for
cracks or damage.
EVAP CANISTER No.1 TUBE IFuel tank-
t o-Canister)
No.4 TUBE ICanister-to-EVAP
purge control solenoid va lve)
3-15