Honda CB900F Service Manual page 40

GENERAL INFORMATION
EXHAUST EMISSION CONTROL SYSTEM (SECONDARY AIR SUPPLY SYSTEM)
The ex haust emission co nt rol system is composed of a lean fue l inj ection setting, and no adjustments sho uld be made except
id le sp eed adjustm ent w it h th e t hro tt le stop screw. Th e exha ust emi ssio n control sy stem is se parate from the cra nkcase emi s-
sio n co ntrol sy stem .
Th e exhaust em iss io n control syst em con sist s of a secondary air supply system that introduces filtered ai r into th e ex ha ust
gase s in th e ex hau st po rt . Fresh air is draw n into the exha ust port by the f unct io n of th e PAIR (Pulse Secon dary A ir Inj ection )
contro l va lve.
Th is charge o f fr esh air prom ot es bu rn ing of th e unburned exha ust ga ses and ch anges a co ns ide rable amoun t of hydrocar-
bons and carbo n monoxide in t o rel at iv ely harmless carbon d ioxide and water v apor.
The reed va lve prevents reverse air flow t hro ug h the sy stem. The PAIR con t rol valve is operat ed by the so le noid valve. Th e
solenoid v alve is co nt rolled by th e PGM-F I un it , and t he fr esh air passa ge is ope n ed/closed according to the running co nd it io n
IECT/IATfT P/M A P senso r and engine revolution).
No adjustments to the second ary air supply system shoul d be made, alt ho ug h pe riod ic inspectio n of the co m po ne nt s
is recommended .
PAIR CHECK VALVE
EXHAUST PORT
THROTTLE BODY
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AIR CLEA NER HOUSING
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FRESHAIR
. . EX HAUST GAS
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